Electrolytic solution, secondary battery, battery pack, electric vehicle, electric power storage system, electric power tool, and electronic apparatus

ABSTRACT

A secondary battery includes: a cathode; an anode; and an electrolytic solution including a cyano compound, the cyano compound including a compound represented by R1-O—C(═O)—O—R2 (R1, R2, or both include a cyano-group-containing group), a compound represented by R3-C(═O)—O—R4 (R4 includes the cyano-group-containing group), or both.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application claims priority to Japanese Priority PatentApplication JP 2012-131649 filed in the Japan Patent Office on Jun. 11,2012, the entire content of which is hereby incorporated by reference.

BACKGROUND

The present application relates to an electrolytic solution, to asecondary battery that uses the electrolytic solution, and to a batterypack, an electric vehicle, an electric power storage system, an electricpower tool, and an electronic apparatus that use the secondary battery.

In recent years, various electronic apparatuses such as mobile phonesand personal digital assistants (PDAs) have been widely used, and it hasbeen demanded to further reduce the size and the weight of theelectronic apparatuses and to achieve their long life. Accordingly, abattery, in particular, a small and light-weight secondary batterycapable of providing high energy density has been developed as anelectric power source. In these days, it has been considered to applysuch a secondary battery to various applications other than theabove-described electronic apparatuses. Typical example of the otherapplications include battery packs attachably and detachably mounted onelectronic apparatuses or the like, electric vehicles such as electricautomobiles, electric power storage systems such as home electric powerservers, and electric power tools such as electric drills.

Secondary batteries have been proposed that utilizes various charge anddischarge principles in order to obtain battery capacity. In particular,secondary batteries that utilize insertion and extraction of electrodereactants and secondary batteries that utilize precipitation anddissolution of electrode reactants have attracted attention, since suchsecondary batteries achieve higher energy density than batteries such aslead batteries and nickel cadmium batteries.

A secondary battery includes a cathode, an anode, and an electrolyticsolution. The electrolytic solution includes a solvent and anelectrolyte salt. The electrolytic solution that functions as anintermediate in charge and discharge reactions largely influencesperformance of the secondary battery. Therefore, in order to improvebattery characteristics, it is considered to add various additives tothe electrolytic solution.

Specifically, when an oxide-based cathode active material is used, acyanoacetate ester such as methyl cyanoacetate is used in order tosuppress decomposition of the electrolytic solution even when an overvoltage of a cathode is increased upon electric charge (for example, seeJapanese Unexamined Patent Application Publication No. 2011-071083). Inorder to improve cycle characteristics, for example, succinonitrile,1,6-dicyano hexane, or the like is used (for example, see JapaneseUnexamined Patent Application Publication No. 2010-225522). In order toimprove ion conductivity, cyano ester or chain cyano ester carbonate isused (for example see US Patent Application Publication No.2005/0123835). The cyano ester is CN—C(CH₃)₂—O—C(═O)—CH₃ or the like,and the chain cyano ester carbonate is CN—C(CH₃)₂—O—C—(═O)—O—CH₃ or thelike. In order to retain stable dissolution state of an electrolyticsolution, a chain saturated hydrocarbon dinitrile compound or the likeis used in which nitrile groups are bonded to both terminals of a chainsaturated hydrocarbon compound (for example, see Japanese UnexaminedPatent Application Publication No. 2011-154783).

SUMMARY

Recently, for example, electronic apparatuses and the like to which asecondary battery is applied have obtained higher performance and morefunctions and have been frequently used. Accordingly, it is desired tofurther improve battery characteristics of the secondary battery.

It is desirable to provide an electrolytic solution, a secondarybattery, a battery pack, an electric vehicle, an electric power storagesystem, an electric power tool, and an electronic apparatus that arecapable of obtaining superior battery characteristics.

According to an embodiment of the present application, there is providedan electrolytic solution including a cyano compound including a compoundrepresented by a following Formula (1), a compound represented by afollowing Formula (2), or both,

where R1 and R2 are each one of a saturated hydrocarbon group, anunsaturated hydrocarbon group, an oxygen-containing saturatedhydrocarbon group, a cyano-group-containing group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another, and the R1, the R2, or both includethe cyano-group-containing group; a cyano group in thecyano-group-containing group is bonded to an oxygen atom (O) at aterminal of a —O—C(═O)—O— bond with one or more carbon atoms (C) inbetween; (A) when one of the R1 and the R2 does not include thecyano-group-containing group but includes an unsaturated carbon bond andthe other of the R1 and the R2 includes the cyano-group-containinggroup, number of the cyano group in the other of the R1 and the R2 isone or larger; (B) when one of the R1 and the R2 include neither thecyano-group-containing group nor the unsaturated carbon bond and theother of the R1 and the R2 includes the cyano-group-containing group andthe unsaturated carbon bond, the number of the cyano group in the otherof the R1 and the R2 is one or larger; and (C) when one of the R1 andthe R2 include neither the cyano-group-containing group nor theunsaturated carbon bond and the other of the R1 and the R2 includes thecyano-group-containing group but does not include the unsaturated carbonbond, the number of the cyano group in the other of the R1 and the R2 istwo or larger,

where R3 is one of a saturated hydrocarbon group, an unsaturatedhydrocarbon group, an oxygen-containing saturated hydrocarbon group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another; R4 is one ofa cyano-group-containing group, halogenated groups thereof, and groupseach obtained by bonding two or more of the foregoing groups to oneanother; a cyano group in the cyano-group-containing group is bonded toan oxygen atom at a terminal of a —C(═O)—O— bond with one or more carbonatoms in between; (D) when the R3 includes an unsaturated carbon bond,number of the cyano group in the R4 is one or larger; (E) when the R3does not include the unsaturated carbon bond and the R4 includes theunsaturated carbon bond, the number of the cyano group in the R4 is oneor larger; and (F) when the R3 does not include the unsaturated carbonbond and the R4 does not include the unsaturated carbon bond, the numberof the cyano group in the R4 is two or larger.

According to an embodiment of the present application, there is provideda secondary battery including: a cathode; an anode; and an electrolyticsolution including a cyano compound, the cyano compound including acompound represented by a following Formula (1), a compound representedby a following Formula (2), or both,

where R1 and R2 are each one of a saturated hydrocarbon group, anunsaturated hydrocarbon group, an oxygen-containing saturatedhydrocarbon group, a cyano-group-containing group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another, and the R1, the R2, or both includethe cyano-group-containing group; a cyano group in thecyano-group-containing group is bonded to an oxygen atom (O) at aterminal of a —O—C(═O)—O— bond with one or more carbon atoms (C) inbetween; (A) when one of the R1 and the R2 does not include thecyano-group-containing group but includes an unsaturated carbon bond andthe other of the R1 and the R2 includes the cyano-group-containinggroup, number of the cyano group in the other of the R1 and the R2 isone or larger; (B) when one of the R1 and the R2 include neither thecyano-group-containing group nor the unsaturated carbon bond and theother of the R1 and the R2 includes the cyano-group-containing group andthe unsaturated carbon bond, the number of the cyano group in the otherof the R1 and the R2 is one or larger; and (C) when one of the R1 andthe R2 include neither the cyano-group-containing group nor theunsaturated carbon bond and the other of the R1 and the R2 includes thecyano-group-containing group but does not include the unsaturated carbonbond, the number of the cyano group in the other of the R1 and the R2 istwo or larger,

where R3 is one of a saturated hydrocarbon group, an unsaturatedhydrocarbon group, an oxygen-containing saturated hydrocarbon group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another; R4 is one ofa cyano-group-containing group, halogenated groups thereof, and groupseach obtained by bonding two or more of the foregoing groups to oneanother; a cyano group in the cyano-group-containing group is bonded toan oxygen atom at a terminal of a —C(═O)—O— bond with one or more carbonatoms in between; (D) when the R3 includes an unsaturated carbon bond,number of the cyano group in the R4 is one or larger; (E) when the R3does not include the unsaturated carbon bond and the R4 includes theunsaturated carbon bond, the number of the cyano group in the R4 is oneor larger; and (F) when the R3 does not include the unsaturated carbonbond and the R4 does not include the unsaturated carbon bond, the numberof the cyano group in the R4 is two or larger.

According to an embodiment of the present application, there is provideda battery pack including: a secondary battery; a control sectioncontrolling a used state of the secondary battery; and a switch sectionswitching the used state of the secondary battery according to aninstruction of the control section. The secondary battery includes acathode, an anode, and an electrolytic solution including a cyanocompound, the cyano compound including a compound represented by afollowing Formula (1), a compound represented by a following Formula(2), or both,

where R1 and R2 are each one of a saturated hydrocarbon group, anunsaturated hydrocarbon group, an oxygen-containing saturatedhydrocarbon group, a cyano-group-containing group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another, and the R1, the R2, or both includethe cyano-group-containing group; a cyano group in thecyano-group-containing group is bonded to an oxygen atom (O) at aterminal of a —O—C(═O)—O— bond with one or more carbon atoms (C) inbetween; (A) when one of the R1 and the R2 does not include thecyano-group-containing group but includes an unsaturated carbon bond andthe other of the R1 and the R2 includes the cyano-group-containinggroup, number of the cyano group in the other of the R1 and the R2 isone or larger; (B) when one of the R1 and the R2 include neither thecyano-group-containing group nor the unsaturated carbon bond and theother of the R1 and the R2 includes the cyano-group-containing group andthe unsaturated carbon bond, the number of the cyano group in the otherof the R1 and the R2 is one or larger; and (C) when one of the R1 andthe R2 include neither the cyano-group-containing group nor theunsaturated carbon bond and the other of the R1 and the R2 includes thecyano-group-containing group but does not include the unsaturated carbonbond, the number of the cyano group in the other of the R1 and the R2 istwo or larger,

where R3 is one of a saturated hydrocarbon group, an unsaturatedhydrocarbon group, an oxygen-containing saturated hydrocarbon group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another; R4 is one ofa cyano-group-containing group, halogenated groups thereof, and groupseach obtained by bonding two or more of the foregoing groups to oneanother; a cyano group in the cyano-group-containing group is bonded toan oxygen atom at a terminal of a —C(═O)—O— bond with one or more carbonatoms in between; (D) when the R3 includes an unsaturated carbon bond,number of the cyano group in the R4 is one or larger; (E) when the R3does not include the unsaturated carbon bond and the R4 includes theunsaturated carbon bond, the number of the cyano group in the R4 is oneor larger; and (F) when the R3 does not include the unsaturated carbonbond and the R4 does not include the unsaturated carbon bond, the numberof the cyano group in the R4 is two or larger.

According to an embodiment of the present application, there is providedan electric vehicle including: a secondary battery; a conversion sectionconverting electric power supplied from the secondary battery into drivepower; a drive section operating according to the drive power; and acontrol section controlling a used state of the secondary battery. Thesecondary battery includes a cathode, an anode, and an electrolyticsolution including a cyano compound, the cyano compound including acompound represented by a following Formula (1), a compound representedby a following Formula (2), or both,

where R1 and R2 are each one of a saturated hydrocarbon group, anunsaturated hydrocarbon group, an oxygen-containing saturatedhydrocarbon group, a cyano-group-containing group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another, and the R1, the R2, or both includethe cyano-group-containing group; a cyano group in thecyano-group-containing group is bonded to an oxygen atom (O) at aterminal of a —O—C(═O)—O— bond with one or more carbon atoms (C) inbetween; (A) when one of the R1 and the R2 does not include thecyano-group-containing group but includes an unsaturated carbon bond andthe other of the R1 and the R2 includes the cyano-group-containinggroup, number of the cyano group in the other of the R1 and the R2 isone or larger; (B) when one of the R1 and the R2 include neither thecyano-group-containing group nor the unsaturated carbon bond and theother of the R1 and the R2 includes the cyano-group-containing group andthe unsaturated carbon bond, the number of the cyano group in the otherof the R1 and the R2 is one or larger; and (C) when one of the R1 andthe R2 include neither the cyano-group-containing group nor theunsaturated carbon bond and the other of the R1 and the R2 includes thecyano-group-containing group but does not include the unsaturated carbonbond, the number of the cyano group in the other of the R1 and the R2 istwo or larger,

where R3 is one of a saturated hydrocarbon group, an unsaturatedhydrocarbon group, an oxygen-containing saturated hydrocarbon group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another; R4 is one ofa cyano-group-containing group, halogenated groups thereof, and groupseach obtained by bonding two or more of the foregoing groups to oneanother; a cyano group in the cyano-group-containing group is bonded toan oxygen atom at a terminal of a —C(═O)—O— bond with one or more carbonatoms in between; (D) when the R3 includes an unsaturated carbon bond,number of the cyano group in the R4 is one or larger; (E) when the R3does not include the unsaturated carbon bond and the R4 includes theunsaturated carbon bond, the number of the cyano group in the R4 is oneor larger; and (F) when the R3 does not include the unsaturated carbonbond and the R4 does not include the unsaturated carbon bond, the numberof the cyano group in the R4 is two or larger.

According to an embodiment of the present application, there is providedan electric power storage system including: a secondary battery; one ormore electric devices supplied with electric power from the secondarybattery; and a control section controlling the supplying of the electricpower from the secondary battery to the one or more electric devices.The secondary battery includes a cathode, an anode, and an electrolyticsolution including a cyano compound, the cyano compound including acompound represented by a following Formula (1), a compound representedby a following Formula (2), or both,

where R1 and R2 are each one of a saturated hydrocarbon group, anunsaturated hydrocarbon group, an oxygen-containing saturatedhydrocarbon group, a cyano-group-containing group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another, and the R1, the R2, or both includethe cyano-group-containing group; a cyano group in thecyano-group-containing group is bonded to an oxygen atom (O) at aterminal of a —O—C(═O)—O— bond with one or more carbon atoms (C) inbetween; (A) when one of the R1 and the R2 does not include thecyano-group-containing group but includes an unsaturated carbon bond andthe other of the R1 and the R2 includes the cyano-group-containinggroup, number of the cyano group in the other of the R1 and the R2 isone or larger; (B) when one of the R1 and the R2 include neither thecyano-group-containing group nor the unsaturated carbon bond and theother of the R1 and the R2 includes the cyano-group-containing group andthe unsaturated carbon bond, the number of the cyano group in the otherof the R1 and the R2 is one or larger; and (C) when one of the R1 andthe R2 include neither the cyano-group-containing group nor theunsaturated carbon bond and the other of the R1 and the R2 includes thecyano-group-containing group but does not include the unsaturated carbonbond, the number of the cyano group in the other of the R1 and the R2 istwo or larger,

where R3 is one of a saturated hydrocarbon group, an unsaturatedhydrocarbon group, an oxygen-containing saturated hydrocarbon group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another; R4 is one ofa cyano-group-containing group, halogenated groups thereof, and groupseach obtained by bonding two or more of the foregoing groups to oneanother; a cyano group in the cyano-group-containing group is bonded toan oxygen atom at a terminal of a —C(═O)—O— bond with one or more carbonatoms in between; (D) when the R3 includes an unsaturated carbon bond,number of the cyano group in the R4 is one or larger; (E) when the R3does not include the unsaturated carbon bond and the R4 includes theunsaturated carbon bond, the number of the cyano group in the R4 is oneor larger; and (F) when the R3 does not include the unsaturated carbonbond and the R4 does not include the unsaturated carbon bond, the numberof the cyano group in the R4 is two or larger.

According to an embodiment of the present application, there is providedan electric power tool including: a secondary battery; and a movablesection supplied with electric power from the secondary battery. Thesecondary battery includes a cathode, an anode, and an electrolyticsolution including a cyano compound, the cyano compound including acompound represented by a following Formula (1), a compound representedby a following Formula (2), or both,

where R1 and R2 are each one of a saturated hydrocarbon group, anunsaturated hydrocarbon group, an oxygen-containing saturatedhydrocarbon group, a cyano-group-containing group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another, and the R1, the R2, or both includethe cyano-group-containing group; a cyano group in thecyano-group-containing group is bonded to an oxygen atom (O) at aterminal of a —O—C(═O)—O— bond with one or more carbon atoms (C) inbetween; (A) when one of the R1 and the R2 does not include thecyano-group-containing group but includes an unsaturated carbon bond andthe other of the R1 and the R2 includes the cyano-group-containinggroup, number of the cyano group in the other of the R1 and the R2 isone or larger; (B) when one of the R1 and the R2 include neither thecyano-group-containing group nor the unsaturated carbon bond and theother of the R1 and the R2 includes the cyano-group-containing group andthe unsaturated carbon bond, the number of the cyano group in the otherof the R1 and the R2 is one or larger; and (C) when one of the R1 andthe R2 include neither the cyano-group-containing group nor theunsaturated carbon bond and the other of the R1 and the R2 includes thecyano-group-containing group but does not include the unsaturated carbonbond, the number of the cyano group in the other of the R1 and the R2 istwo or larger,

where R3 is one of a saturated hydrocarbon group, an unsaturatedhydrocarbon group, an oxygen-containing saturated hydrocarbon group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another; R4 is one ofa cyano-group-containing group, halogenated groups thereof, and groupseach obtained by bonding two or more of the foregoing groups to oneanother; a cyano group in the cyano-group-containing group is bonded toan oxygen atom at a terminal of a —C(═O)—O— bond with one or more carbonatoms in between; (D) when the R3 includes an unsaturated carbon bond,number of the cyano group in the R4 is one or larger; (E) when the R3does not include the unsaturated carbon bond and the R4 includes theunsaturated carbon bond, the number of the cyano group in the R4 is oneor larger; and (F) when the R3 does not include the unsaturated carbonbond and the R4 does not include the unsaturated carbon bond, the numberof the cyano group in the R4 is two or larger.

According to an embodiment of the present application, there is providedan electronic apparatus including a secondary battery as an electricpower supply source. The secondary battery includes a cathode, an anode,and an electrolytic solution including a cyano compound, the cyanocompound including a compound represented by a following Formula (1), acompound represented by a following Formula (2), or both,

where R1 and R2 are each one of a saturated hydrocarbon group, anunsaturated hydrocarbon group, an oxygen-containing saturatedhydrocarbon group, a cyano-group-containing group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another, and the R1, the R2, or both includethe cyano-group-containing group; a cyano group in thecyano-group-containing group is bonded to an oxygen atom (O) at aterminal of a —O—C(═O)—O— bond with one or more carbon atoms (C) inbetween; (A) when one of the R1 and the R2 does not include thecyano-group-containing group but includes an unsaturated carbon bond andthe other of the R1 and the R2 includes the cyano-group-containinggroup, number of the cyano group in the other of the R1 and the R2 isone or larger; (B) when one of the R1 and the R2 include neither thecyano-group-containing group nor the unsaturated carbon bond and theother of the R1 and the R2 includes the cyano-group-containing group andthe unsaturated carbon bond, the number of the cyano group in the otherof the R1 and the R2 is one or larger; and (C) when one of the R1 andthe R2 include neither the cyano-group-containing group nor theunsaturated carbon bond and the other of the R1 and the R2 includes thecyano-group-containing group but does not include the unsaturated carbonbond, the number of the cyano group in the other of the R1 and the R2 istwo or larger,

where R3 is one of a saturated hydrocarbon group, an unsaturatedhydrocarbon group, an oxygen-containing saturated hydrocarbon group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another; R4 is one ofa cyano-group-containing group, halogenated groups thereof, and groupseach obtained by bonding two or more of the foregoing groups to oneanother; a cyano group in the cyano-group-containing group is bonded toan oxygen atom at a terminal of a —C(═O)—O— bond with one or more carbonatoms in between; (D) when the R3 includes an unsaturated carbon bond,number of the cyano group in the R4 is one or larger; (E) when the R3does not include the unsaturated carbon bond and the R4 includes theunsaturated carbon bond, the number of the cyano group in the R4 is oneor larger; and (F) when the R3 does not include the unsaturated carbonbond and the R4 does not include the unsaturated carbon bond, the numberof the cyano group in the R4 is two or larger.

As used herein, the term “cyano-group-containing group” collectivelyrefers to groups that each include one or more cyano groups in partthereof. The cyano group in the “cyano-group-containing group” isindirectly bonded to the oxygen atom at the terminal of the —O—C(═O)—O—bond or of the —C(═O)—O— bond with one or more carbon atoms in between,as described above. Accordingly, the cyano group (—CN) is notencompassed by “cyano-group-containing group” described herein since thecyano group itself is directly bonded to the oxygen atom at the terminal

Further, the term “halogenated group” refers to a group obtained bysubstituting each of part or all of hydrogen groups in a group such as asaturated hydrocarbon group by a halogen group.

According to the electrolytic solution and the secondary batteryaccording to the embodiments of the present application, theelectrolytic solution includes the above-described cyano compound.Therefore, superior battery characteristics are obtained. Further,similar effects are obtained in the battery pack, in the electricvehicle, in the electric power storage system, in the electric powertool, and in the electronic apparatus according to the embodiments ofthe present application.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, and are intended toprovide further explanation of the technology as claimed.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying drawings are included to provide a furtherunderstanding of the disclosure, and are incorporated in and constitutea part of this specification. The drawings illustrate embodiments and,together with the specification, serve to explain the principles of thetechnology.

FIG. 1 is a cross-sectional view illustrating a configuration of asecondary battery (cylindrical type) provided with an electrolyticsolution of a first embodiment of the present application.

FIG. 2 is a cross-sectional view illustrating an enlarged part of aspirally wound electrode body illustrated in FIG. 1.

FIG. 3 is a perspective view illustrating a configuration of anothersecondary battery (laminated film type) provided with the electrolyticsolution of the first embodiment of the present application.

FIG. 4 is a cross-sectional view of a spirally wound electrode bodyshown in FIG. 3 taken along a line IV-IV.

FIG. 5 is a block diagram illustrating a configuration of an applicationexample (battery pack) of the secondary battery.

FIG. 6 is a block diagram illustrating a configuration of an applicationexample (electric vehicle) of the secondary battery.

FIG. 7 is a block diagram illustrating a configuration of an applicationexample (electric power storage system) of the secondary battery.

FIG. 8 is a block diagram illustrating a configuration of an applicationexample (electric power tool) of the secondary battery.

DETAILED DESCRIPTION

Preferred embodiments of the present application will be hereinafterdescribed in detail with reference to the drawings. Description will begiven in the following order.

1. First Embodiment/Electrolytic Solution and Secondary Battery

(cyano compound: the number of cyano group is limited)

1-1. Lithium Ion Secondary Battery (Cylindrical Type)

1-2. Lithium Ion Secondary Battery (Laminated Film Type)

1-3. Lithium Metal Secondary Battery (Cylindrical Type and LaminatedFilm Type)

2. Second Embodiment/Secondary Battery

(cyano compound: the number of cyano group is not limited+metal-basedmaterial)

2-1. Lithium Ion Secondary Battery (Cylindrical Type)

2-2. Lithium Ion Secondary Battery (Laminated Film Type)

3. Third Embodiment/Electrolytic Solution and Secondary Battery

(cyano compound: the number of cyano group is not limited+non-cyanocompound)

3-1. Lithium Ion Secondary Battery (Cylindrical Type)

3-2. Lithium Ion Secondary Battery (Laminated Film Type)

3-3. Lithium Metal Secondary Battery (Cylindrical Type and LaminatedFilm Type)

4. Applications of Secondary Battery

4-1. Battery Pack

4-2. Electric Vehicle

4-3. Electric Power Storage System

4-4. Electric Power Tool

1. First Embodiment/Electrolytic Solution and Secondary Battery CyanoCompound: The Number of Cyano Group is Limited

First, description will be given of an electrolytic solution and asecondary battery of a first embodiment of the present application.

[1-1. Lithium Ion Secondary Battery (Cylindrical Type)]

FIG. 1 and FIG. 2 each illustrate a cross-sectional configuration of asecondary battery that uses the electrolytic solution of the presentembodiment. It is to be noted that FIG. 2 illustrates an enlarged partof a spirally wound electrode body 20 shown in FIG. 1.

[General Configuration of Secondary Battery]

The secondary battery described herein is a lithium secondary battery(lithium ion secondary battery) in which a capacity of an anode 22 isobtained by insertion and extraction of Li that is an electrodereactant, and is of a so-called cylindrical type.

In the present secondary battery, for example, the spirally woundelectrode body 20 and a pair of insulating plates 12 and 13 may becontained in a battery can 11 that has a shape of a substantially hollowcylinder. The spirally wound electrode body 20 may be formed of, forexample, a cathode 21 and the anode 22 that are laminated with aseparator 23 in between and then are spirally wound.

The battery can 11 has a hollow structure in which one end of thebattery can 11 is closed and the other end thereof is open. The batterycan 11 may be formed of, for example, iron, aluminum, an alloy thereof,and/or the like. The surface of the battery can 11 may be plated with,for example, nickel and/or the like. The pair of insulating plates 12and 13 are arranged so as to sandwich the spirally wound electrode body20 in between, and extend perpendicularly with respect to a spirallywound periphery surface of the spirally wound electrode body 20.

At the open end of the battery can 11, a battery cover 14, a safetyvalve mechanism 15, and a positive temperature coefficient device (PTCdevice) 16 are attached by being swaged with a gasket 17, and therebythe battery can 11 is hermetically sealed. The battery cover 14 may beformed of, for example, a material similar to that of the battery can11. The safety valve mechanism 15 and the PTC device 16 are providedinside the battery cover 14. The safety valve mechanism 15 iselectrically connected to the battery cover 14 through the PTC device16. In the safety valve mechanism 15, when an internal pressure becomesa certain level or higher, for example, due to reasons such as internalshort circuit and external heating, a disk plate 15A inverts to cutelectric connection between the battery cover 14 and the spirally woundelectrode body 20. The PTC device 16 prevents abnormal heating resultingfrom a large current. The PTC device 16 is so configured that theresistance thereof is increased as the temperature rises. The gasket 17may be formed of, for example, an insulating material. The surface ofthe gasket 17 may be coated with asphalt, for example.

A center pin 24 may be inserted in the center of the spirally woundelectrode body 20. It is to be noted that the center pin 24 may not beinserted therein. The cathode 21 may be connected to, for example, acathode lead 25 formed of an electrically-conductive material such asaluminum, and the anode 22 may be connected to, for example, an anodelead 26 formed of an electrically-conductive material such as nickel.The cathode lead 25 may be, for example, welded to the safety valvemechanism 15 and may be electrically connected to the battery cover 14.The anode lead 26 may be, for example, electrically connected to thebattery can 11 by being welded to the battery can 11.

[Cathode]

The cathode 21 includes a cathode active material layer 21B on one orboth sides of a cathode current collector 21A. The cathode currentcollector 21A may be formed of, for example, an electrically-conductivematerial such as aluminum, nickel, and stainless steel.

The cathode active material layer 21B includes, as a cathode activematerial, one or more of cathode materials that are capable of insertingand extracting lithium ions. The cathode active material layer 21B mayinclude other materials such as a cathode binder and a cathodeconductive agent where appropriate.

The cathode material is preferably a lithium-containing compound sincehigh energy density is obtained thereby. The lithium-containing compoundmay be, for example, a compound such as a lithium transition metalcomposite oxide and a lithium transition metal phosphate compound. Thelithium transition metal composite oxide is an oxide that includes Liand one or more transition metal elements as constituent elements. Thelithium transition metal phosphate compound is a phosphate compound thatincludes Li and one or more transition metal elements as constituentelements. In particular, the transition metal element is preferably oneor more of elements such as Co, Ni, Mn, and Fe since a higher voltage isobtained thereby. The chemical formulas of the compounds may be, forexample, represented by one of Li_(x)M1O₂ and Li_(y)M2PO₄. In theformulas, M1 and M2 each represent one or more transition metalelements. Values of x and y vary depending on the charge and dischargestates of the battery. To give an example, the values of x and y maysatisfy 0.05≦x≦1.10 and 0.05≦y≦1.10.

Examples of the lithium transition metal composite oxide may includeLiCoO₂, LiNiO₂, and lithium-nickel-based composite oxides represented bythe following Formula (30). Examples of the lithium transition metalphosphate compound may include LiFePO₄ and LiFe_(1-u)Mn_(u)PO₄ (u<1)since high battery capacity is obtained and superior cyclecharacteristics are also obtained thereby.

LiNi_(1-z)M_(z)O₂  (30)

(M is one or more of Co, Mn, Fe, Al, V, Sn, Mg, Ti, Sr, Ca, Zr, Mo, Tc,Ru, Ta, W, Re, Yb, Cu, Zn, Ba, B, Cr, Si, Ga, P, Sb, and Nb, and zsatisfies 0.005<z<0.5.)

Other than the above-described materials, the cathode material may be,for example, oxides, disulfides, calcogenides, andelectrically-conductive polymers. Examples of the oxides may includetitanium oxide, vanadium oxide, and manganese dioxide. Examples of thedisulfides may include titanium disulfide and molybdenum sulfide.Examples of the calcogenides may include niobium selenide. Examples ofthe electrically-conductive polymer may include sulfur, polyaniline, andpolythiophene. It is to be noted that the cathode material is notlimited to the materials described above and may be other materials.

The cathode binder may be, for example, one or more of materials such assynthetic rubbers and polymer materials. Examples of the syntheticrubbers may include styrene-butadiene-based rubber, fluorine-basedrubber, and ethylene propylene diene. Examples of the polymer materialsmay include polyvinylidene fluoride and polyimide.

The cathode conductive agent may be, for example, one or more ofmaterials such as carbon materials. Examples of the carbon materials mayinclude graphite, carbon black, acetylene black, and Ketjen black. It isto be noted that the cathode conductive agent may be, for example, metalmaterials, electrically-conductive polymers, or the like as long as thematerial has electrical conductivity.

[Anode]

The anode 22 includes an anode active material layer 22B on one or bothsides of an anode current collector 22A.

The anode current collector 22A may be formed, for example, of anelectrically-conductive material such as copper, nickel, and stainlesssteel. A surface of the anode current collector 22A is preferablyroughened, since adhesive characteristics of the anode active materiallayer 22B with respect to the anode current collector 22A is improveddue to a so-called anchor effect. In this case, it may be enough thatthe surface of the anode current collector 22A in a region opposed tothe anode active material layer 22B is roughened at least. Examples ofroughening methods may include a method of forming fine particles byutilizing electrolytic treatment. The electrolytic treatment is a methodof providing concavities and convexities on the anode current collector22A by forming fine particles thereon by using an electrolytic method inan electrolytic bath. A copper foil fabricated by the electrolyticmethod is generally called “electrolytic copper foil”.

The anode active material layer 22B includes, as an anode activematerial, one or more of anode materials that are capable of insertingand extracting lithium ions. The anode active material layer 22B mayinclude other materials such as an anode binder and an anode conductiveagent where appropriate. Details of the anode binder and the anodeconductive agent may be, for example, similar to those of the cathodebinder and the cathode conductive agent, respectively. It is to be notedthat a chargeable capacity of the anode material is preferably largerthan a discharge capacity of the cathode 21 so as to preventunintentional precipitation of lithium metal on the anode 22 duringelectric charge. Specifically, an electrochemical equivalent of theanode material capable of inserting and extracting lithium ions ispreferably larger than an electrochemical equivalent of the cathode 21.

The anode material may be, for example, a carbon material. One reasonfor this is that, in the carbon material, a change in crystal structureupon insertion and extraction of lithium ions is extremely small, andtherefore, high energy density and superior cycle characteristics areobtainable. Another reason is that the carbon material also functions asan anode conductive agent. Examples of the carbon material may includegraphitizable carbon, non-graphitizable carbon in which the spacing of(002) plane is 0.37 nm or larger, and graphite in which the spacing of(002) plane is 0.34 nm or smaller. More specifically, examples of thecarbon material may include pyrolytic carbons, cokes, glassy carbonfiber, an organic polymer compound fired body, activated carbon, andcarbon blacks. Of the foregoing, examples of the cokes may include pitchcoke, needle coke, and petroleum coke. The organic polymer compoundfired body is a material in which a polymer compound such as phenolresin and furan resin is fired (carbonized) at appropriate temperature.In addition to the above-mentioned materials, the carbon material may below crystalline carbon or amorphous carbon that is heat-treated attemperature of about 1000° C. or lower. It is to be noted that the shapeof the carbon material may be a fibrous shape, a spherical shape, agranular shape, a scale-like shape, etc.

Alternatively, the anode material may be, for example, a material(metal-based material) that includes one or more of metal elements andmetalloid elements as constituent elements since high energy density isobtained thereby. The metal-based material may be a simple substance, analloy, or a compound, may be two or more thereof, or may have one ormore phases thereof in part or all of the material. “Alloy” includes amaterial that includes one or more metal elements and one or moremetalloid elements, in addition to a material configured of two or moremetal elements. Further, “alloy” may contain a non-metal element.Example of a texture thereof may include a solid solution, a eutecticcrystal (eutectic mixture), an intermetallic compound, and a texture inwhich two or more thereof coexist.

The above-described metal element and metalloid element may be, forexample, one or more of metal elements and metalloid elements that arecapable of forming an alloy with Li. Specific examples thereof mayinclude Mg, B, Al, Ga, In, Si, Ge, Sn, Pb, Bi, Cd, Ag, Zn, Hf, Zr, Y,Pd, and Pt. In particular, Si, Sn, or both are preferably used since Siand Sn have high ability of inserting and extracting lithium ions, andtherefore, high energy density is obtained.

A material that includes Si, Sn, or both may be a simple substance, analloy, or a compound of Si or Sn; two or more thereof; or a materialthat has one or more phases thereof in part or all of the material. Itis to be noted that, as used herein the term “simple substance” merelyrefers to a simple substance in a general meaning (a small amount ofimpurity may be contained therein), and does not necessarily refer to asimple substance of purity 100%.

The alloy of Si may include, for example, one or more of elements suchas Sn, Ni, Cu, Fe, Co, Mn, Zn, In, Ag, Ti, Ge, Bi, Sb, and Cr asconstituent elements other than Si. The compounds of Si may include, forexample, one or more elements such as C and O as constituent elementsother than Si. It is to be noted that the compound of Si may include,for example, one or more of the elements described for the alloys of Sias constituent elements other than Si.

Specific examples of the alloys and the compounds of Si include SiB₄,SiB₆, Mg₂Si, Ni₂Si, TiSi₂, MoSi₂, CoSi₂, NiSi₂, CaSi₂, CrSi₂, Cu₅Si,FeSi₂, MnSi₂, NbSi₂, TaSi₂, VSi₂, WSi₂, ZnSi₂, SiC, Si₃N₄, Si₂N₂O,SiO_(v) (0≦v≦2), and LiSiO. It is to be noted that v in SiO_(v) maysatisfy 0.2<v<1.4.

The alloy of Sn may include, for example, one or more of elements suchas Si, Ni, Cu, Fe, Co, Mn, Zn, In, Ag, Ti, Ge, Bi, Sb, and Cr asconstituent elements other than Sn. The compound of Sn may include oneor more of elements such as C and O as constituent elements other thanSn. It is to be noted that the compound of Sn may include, for example,one or more of the elements described for the alloys of Sn asconstituent elements other than Sn. Specific examples of the alloys andthe compounds of Sn include SnO_(w) (0<w≦2), SnSiO₃, LiSnO, and Mg₂Sn.

Further, as a material that includes Sn as a constituent element, forexample, a material that includes Sn as a first constituent element andincludes second and third constituent elements in addition thereto ispreferable. The second constituent element may be, for example, one ormore of elements such as Co, Fe, Mg, Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, Zr,Nb, Mo, Ag, In, Ce, Hf, Ta, W, Bi, and Si. The third constituent elementmay be, for example, one or more of elements such as B, C, Al, and P.One reason for this is that, by including the second and thirdconstituent elements, for example, high battery capacity, superior cyclecharacteristics, and the like are obtained.

In particular, a material (SnCoC-containing material) that includes Sn,Co, and C as constituent elements is preferable. In the SnCoC-containingmaterial, for example, the C content may be from 9.9 mass % to 29.7 mass% both inclusive, and the ratio of Sn and Co contents (Co/(Sn+Co)) maybe from 20 mass % to 70 mass % both inclusive, since high energy densityis obtained thereby.

The SnCoC-containing material includes a phase that includes Sn, Co, andC. The phase is preferably low crystalline or amorphous. The phase is areactive phase capable of reacting with Li, and therefore, furthersuperior characteristics are obtained due to the presence of thereactive phase. A half bandwidth of a diffraction peak of the phaseobtained by X-ray diffraction is preferably 1° or larger at adiffraction angle of 2θ in the case where a CuKα ray is used as aspecific X ray and the sweep rate is 1°/min. This allows lithium ions tobe inserted and extracted more smoothly, and reduces reactivity with theelectrolytic solution. It is to be noted that the SnCoC-containingmaterial may include a phase that includes the simple substance of eachconstituent element or part of the constituent elements in addition to alow-crystalline phase or an amorphous phase.

Whether or not the diffraction peak obtained by X-ray diffractioncorresponds to a reactive phase capable of reacting with Li is easilydetermined by comparing X-ray diffraction charts before and afterelectrochemical reaction with Li. For example, when the position of thediffraction peak before the electrochemical reaction with Li isdifferent from that after the electrochemical reaction, the diffractionpeak corresponds to a reactive phase capable of reacting with Li. Inthis case, for example, the diffraction peak of a low-crystallinereactive phase or an amorphous reactive phase may be detected within arange of 2θ=20° to 50°. Such a reactive phase may include, for example,the above-described constituent elements, and is considered to bechanged to be low crystalline or amorphous mainly due to the presence ofC.

In the SnCoC-containing material, part or all of C which is aconstituent element is preferably bonded to a metal element or ametalloid element which is another constituent element. Thus,aggregation and crystallization of, for example, materials such as Sn issuppressed. The bonding state of elements may be determined, forexample, by X-ray photoelectron spectroscopy (XPS). In acommercially-available apparatus, for example, an Al—Kα ray, an Mg—Kαray, etc. may be used as a soft X ray. In the case where part or all ofC is bonded to an element such as a metal element and a metalloidelement, the peak of a composite wave of the 1 s orbit (C1s) of C isobserved in a region lower than 284.5 eV. It is to be noted that energycalibration is performed so as to allow the peak of the 4f orbit (Au4f)of an Au atom to be obtained at 84.0 eV. In this case, typically, sincesurface contamination carbon is present on a material surface, the peakof C1s of the surface contamination carbon is defined at 284.8 eV, andis used as an energy reference. In XPS measurement, the waveform of thepeak of C1s is obtained in a form that includes the peak of the surfacecontamination carbon and the peak of carbon in the SnCoC-containingmaterial. Therefore, the peak of the surface contamination carbon andthe peak of carbon in the SnCoC-containing material are separated, forexample, by analysis with the use of commercially-available software. Inthe analysis of the waveform, the position of a main peak that is in aregion closer to the lowest binding energy is used as the energyreference (284.8 eV).

It is to be noted that SnCoC-containing material is not limited to amaterial (SnCoC) that includes only Sn, Co, and C as constituentelements. The SnCoC-containing material may further include, forexample, one or more of elements such as Si, Fe, Ni, Cr, In, Nb, Ge, Ti,Mo, Al, P, Ga, and Bi as constituent elements in addition to Sn, Co, andC.

In addition to the SnCoC-containing material, a material(SnCoFeC-containing material) that includes Sn, Co, Fe, and C asconstituent elements is also preferable. The composition of theSnCoFeC-containing material may be any composition. To give an example,in the composition in which the Fe content is set smaller, the C contentmay be from 9.9 mass % to 29.7 mass % both inclusive, the Fe content maybe from 0.3 mass % to 5.9 mass % both inclusive, and the ratio ofcontents of Sn and Co (Co/(Sn+Co)) may be from 30 mass % to 70 mass %both inclusive. Further, for example, in the composition in which the Fecontent is set larger, the C content may be from 11.9 mass % to 29.7mass % both inclusive, the ratio of contents of Sn, Co, and Fe((Co+Fe)/(Sn+Co+Fe)) may be from 26.4 mass % to 48.5 mass % bothinclusive, and the ratio of contents of Co and Fe (Co/(Co+Fe)) may befrom 9.9 mass % to 79.5 mass % both inclusive. One reason for these isthat, in such a composition range, high energy density is obtained. Thephysical properties (such as half bandwidth) of the SnCoFeC-containingmaterial are similar to those of the above-described SnCoC-containingmaterial.

In addition to the above-mentioned materials, the anode material may be,for example, a material such as a metal oxide and a polymer compound.Examples of the metal oxide may include iron oxide, ruthenium oxide, andmolybdenum oxide. Examples of the polymer compound may includepolyacetylene, polyaniline, and polypyrrole.

The anode active material layer 22B may be formed, for example, by acoating method, a vapor-phase method, a liquid-phase method, a sprayingmethod, a firing method (sintering method), or a combination of two ormore of these methods. The coating method may be, for example, a methodin which, after a particulate (powder) anode active material is mixedwith materials such as the anode binder, the mixture is dispersed in asolvent such as an organic solvent, and the anode current collector 22Ais coated with the resultant. Examples of the vapor-phase method mayinclude a physical deposition method and a chemical deposition method.More specifically, examples thereof may include a vacuum evaporationmethod, a sputtering method, an ion plating method, a laser ablationmethod, a thermal chemical vapor deposition method, a chemical vapordeposition (CVD) method, and a plasma chemical vapor deposition method.Examples of the liquid-phase method may include an electrolytic platingmethod and an electroless plating method. The spraying method may be,for example, a method in which an anode active material in a fused stateor a semi-fused state is sprayed onto the anode current collector 22A.The firing method may be, for example, a method in which, after theanode current collector 22A is coated by a coating method, heattreatment is performed at temperature higher than the melting point ofthe materials such as the anode binder. As the firing method, forexample, an atmosphere firing method, a reactive firing method, a hotpress firing method, etc. may be used.

In the present secondary battery, as described above, in order toprevent unintentional precipitation of lithium metal on the anode 22 inthe middle of charge, the electrochemical equivalent of the anodematerial capable of inserting and extracting lithium ions is larger thanthe electrochemical equivalent of the cathode. Further, when the opencircuit voltage (that is, a battery voltage) at the time ofcompletely-charged state is equal to or larger than 4.25 V, theextraction amount of lithium ions per unit mass is larger than that inthe case where the open circuit voltage is 4.20 V even if the samecathode active material is used. Therefore, amounts of the cathodeactive material and the anode active material are adjusted in accordancetherewith. Thus, high energy density is obtained.

[Separator]

The separator 23 separates the cathode 21 from the anode 22, and therebypasses lithium ions while preventing current short circuit resultingfrom contact of the both electrodes. The separator 23 may be, forexample, a porous film made of a material such as a synthetic resin andceramics. The separator 23 may be a laminated film in which two or moreporous films are laminated. Examples of the synthetic resin may includepolytetrafluoroethylene, polypropylene, and polyethylene.

In particular, the separator 23 may include, for example, a polymercompound layer on one or both surfaces of the above-described porousfilm (base material layer) since adhesive characteristics of theseparator 23 with respect to the cathode 21 and the anode 22 areimproved, and therefore, distortion of the spirally wound electrode body20 is suppressed. Hence, a decomposition reaction of the electrolyticsolution is suppressed, and liquid leakage of the electrolytic solutionwith which the base material layer is impregnated is suppressed.Accordingly, the resistance of the secondary battery is less likely tobe increased even if the battery is charged and discharged repeatedly,and battery swollenness is suppressed.

The polymer compound layer may include, for example, a polymer materialsuch as polyvinylidene fluoride since such a polymer material hassuperior physical strength and is electrochemically stable. However, thepolymer material is not limited to polyvinylidene fluoride. In a casewhere the polymer compound layer is formed, for example, solution inwhich the polymer material is dissolved may be prepared, and then thebase material layer may be coated with the solution and may be dried. Itis to be noted that the base material layer may be soaked in thesolution and then may be dried.

[Electrolytic Solution]

The separator 23 is impregnated with an electrolytic solution that is anliquid electrolyte. The electrolytic solution includes one or more ofcyano compounds. The cyano compound includes a compound represented bythe following Formula (1), a compound represented by the followingFormula (2), or both. It is to be noted that the electrolytic solutionmay include other materials such as a solvent and an electrolyte salt.

(R1 and R2 are each one of a saturated hydrocarbon group, an unsaturatedhydrocarbon group, an oxygen-containing saturated hydrocarbon group, acyano-group-containing group, halogenated groups of the foregoinggroups, and groups each obtained by bonding two or more of the foregoinggroups to one another, and R1, R2, or both include thecyano-group-containing group. A cyano group in thecyano-group-containing group is bonded to an oxygen atom (O) at aterminal of a —O—C(═O)—O— bond with one or more carbon atoms (C) inbetween. It is to be noted that (A) when one of R1 and R2 does notinclude the cyano-group-containing group but includes an unsaturatedcarbon bond and the other of R1 and R2 includes thecyano-group-containing group, the number of the cyano group in the otherof R1 and R2 is one or larger. (B) When one of R1 and R2 include neitherthe cyano-group-containing group nor the unsaturated carbon bond and theother of R1 and R2 includes the cyano-group-containing group and theunsaturated carbon bond, the number of the cyano group in the other ofR1 and R2 is one or larger. (C) When one of R1 and R2 include neitherthe cyano-group-containing group nor the unsaturated carbon bond and theother of R1 and R2 includes the cyano-group-containing group but doesnot include the unsaturated carbon bond, the number of the cyano groupin the other of R1 and R2 is two or larger.)

(R3 is one of a saturated hydrocarbon group, an unsaturated hydrocarbongroup, an oxygen-containing saturated hydrocarbon group, halogenatedgroups of the foregoing groups, and groups each obtained by bonding twoor more of the foregoing groups to one another. R4 is one of acyano-group-containing group, a halogenated group thereof, and groupseach obtained by bonding two or more of the foregoing groups to oneanother. A cyano group in the cyano-group-containing group is bonded toan oxygen atom at a terminal of a —C(═O)—O— bond with one or more carbonatoms in between. It is to be noted that (D) when R3 includes anunsaturated carbon bond, the number of the cyano group in R4 is one orlarger. (E) When R3 does not include the unsaturated carbon bond and R4includes the unsaturated carbon bond, the number of the cyano group inR4 is one or larger. (F) When R3 does not include the unsaturated carbonbond and R4 does not include the unsaturated carbon bond, the number ofthe cyano group in R4 is two or larger.)

As used herein, the term “cyano-group-containing group” collectivelyrefers to groups that each include one or more cyano groups in partthereof as described above. The cyano group (—CN) is not included in“cyano-group-containing group” described herein. Further, the term“halogenated group” refers to a group obtained by substituting each ofpart or all of hydrogen groups in a group such as a saturatedhydrocarbon group by a halogen group.

The cyano compound collectively refers to compounds that each includeone or more cyano groups (—CN). More specifically, the compoundrepresented by Formula (1) includes an carbonate-ester type bond(—O—C(═O)—O—) as a skeleton and the compound represented by Formula (2)includes an ester type bond (—C(═O)—O—) as a skeleton. Hereinafter, theformer compound and the latter compound will be referred to as“carbonate-ester type cyano compound” and “ester type cyano compound”,respectively, and the both compounds will be collectively referred to as“cyano compound” where appropriate.

One reason why the electrolytic solution includes the cyano compound isthat chemical stability is improved thereby compared to in a case wherethe cyano compound is not included, and therefore, a decompositionreaction is suppressed. In more detail, a rigid film is formed mainly ona surface of the anode 22 resulting from the cyano compound uponelectric charge and discharge, and this suppresses a decompositionreaction of the electrolytic solution that is caused by the presence ofhighly-reactive anode 22. Accordingly, even when a secondary battery isrepeatedly charged and discharged and is stored, decrease in dischargecapacity is suppressed. Such a tendency is remarkable, in particular,when the secondary battery is charged and discharged or is stored undersevere temperature environment such as high temperature environment.

In Formula (1), the types of R1 and R2 are not particularly limited aslong as R1 and R2 are each one of the saturated hydrocarbon group, theunsaturated hydrocarbon group, the oxygen-containing saturatedhydrocarbon group, the cyano-group-containing group, the halogenatedgroups of the foregoing groups, and the groups each obtained by bondingtwo or more of the foregoing groups to one another as described above.It is to be noted that R1 and R2 may be the same type of group or may bedifferent types of group. Further, R1 and R2 may be bonded to each otherand the bonded R1 and R2 may form a ring.

However, the following two conditions are necessary. The first conditionis that R1, R2, or both include the cyano-group-containing group (thatis, the cyano group). Therefore, only R1 may include the cyano group,only R2 may include the cyano group, or both R1 and R2 may each includethe cyano group. The second condition is that a cyano group in thecyano-group-containing group is bonded to an oxygen atom at a terminalof a —O—C(═O)—O— bond with one or more carbon atoms in between. In otherwords, the cyano group is not directly bonded to the oxygen atom and isindirectly bonded to the oxygen atom with a carbon atom in between. Onereason for this is that, as will be described later, the above-describedadvantages are obtained independently of types of R1 and R2 since thecarbonate-ester type cyano compound includes the predetermined number ofcyano groups and the cyano group is indirectly bonded to the oxygen atomwith a carbon atom in between. The number of carbon atom that isinterposed between the cyano group and the oxygen atom is notparticularly limited but is preferably not excessively large sinceproperties such as solubility and compatibility of the cyano compoundare secured thereby. More specifically, the number of carbon atom ispreferably 20 or smaller.

Moreover, the number of the above-described cyano group is limiteddepending on the following cases (cases A to C). Specifically, when eachof R1 and R2 include the cyano group, the number (total number) of cyanogroup is not limited. On the other hand, when only one of R1 and R2includes the cyano group, the number (total number) of the cyano groupdiffers between the cases A to C.

In the case A where one of R1 and R2 does not include the cyano groupbut includes an unsaturated carbon bond (one or more carbon-carbondouble bonds or carbon-carbon triple bonds), the number of cyano groupin the other of R1 and R2 that includes the cyano group is one orlarger. One reason for this is that, when one of R1 and R2 includes theunsaturated carbon bond, a film resulting from the cyano compound iseasily formed intrinsically, and therefore, it is enough that at leastone cyano group that contributes to reactivity of the cyano compound ispresent. The type of the one of R1 and R2 in this case may be one of,for example, an unsaturated hydrocarbon group, halogenated groupsthereof, groups each obtained by bonding two or more of groups includingthe foregoing groups to one another, etc. The other of R1 and R2 thatincludes the cyano group may include an unsaturated carbon bond or maynot include an unsaturated carbon bond.

In the case B where one of R1 and R2 does not include the cyano group orthe unsaturated carbon bond and the other of R1 and R2 that includes thecyano group includes the unsaturated carbon bond, the number of cyanogroup in the other of R1 and R2 is one or larger. One reason for this isthat, when one of R1 and R2 does not include the unsaturated carbon bondbut the other of R1 and R2 includes the unsaturated carbon bond, a filmresulting from the cyano compound is easily formed intrinsically, andtherefore, it is enough that at least one cyano group that contributesto reactivity of the cyano compound is present. The type of the one ofR1 and R2 in this case may be one of, for example, a saturatedhydrocarbon group, an oxygen-containing hydrocarbon group, halogenatedgroups of the foregoing groups, and groups each obtained by bonding twoor more of groups including the foregoing groups to one another, etc.The type of the other of R1 and R2 that includes the cyano group and theunsaturated carbon bond will be described later.

In the case C where one of R1 and R2 include neither the cyano group northe unsaturated carbon bond and the other of R1 and R2 that includes thecyano group does not include the unsaturated carbon bond, the number ofcyano group in the other of R1 and R2 is two or larger. One reason forthis is that, when either of R1 and R2 does not include the unsaturatedcarbon bond, a film resulting from the cyano compound is less likely tobe formed intrinsically, and therefore, two or more cyano groups arenecessary that contribute to reactivity of the cyano compound. The typeof the one of R1 and R2 in this case may be one of, for example, asaturated hydrocarbon group, an oxygen-containing hydrocarbon group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of groups including the foregoing groups to oneanother, etc. The type of the other of R1 and R2 that includes the cyanogroup but does not include the unsaturated carbon bond will be describedlater.

In Formula (2), the type of R3 is not particularly limited as long as R3is one of a saturated hydrocarbon group, an unsaturated hydrocarbongroup, an oxygen-containing saturated hydrocarbon group, halogenatedgroups of the foregoing groups, and groups each obtained by bonding twoor more of the foregoing groups to one another as described above.Further, the type of R4 is not particularly limited as long as R4 is oneof a cyano-group-containing group, halogenated groups thereof, andgroups each obtained by bonding two or more of the foregoing groups toone another as described above. It is to be noted that R3 and R4 may bebonded to each other and the bonded R3 and R4 may form a ring.

However, as in the carbonate-ester type cyano compound, it is made acondition that a cyano group in the cyano-group-containing group isbonded to an oxygen atom at a terminal of a —C(═O)—O— bond with one ormore carbon atoms in between. One reason for this is that, as will bedescribed later, the above-described advantages are obtainedindependently of the type of R3 since the ester type cyano compoundincludes a predetermined number of cyano groups and the cyano group isindirectly bonded to an oxygen atom with a carbon atom in between.

Moreover, the number of the above-described cyano group is limiteddepending on the following cases (cases D to F). Specifically, thenumber (total number) of cyano group in R4 that includes the cyano groupdiffers between the cases D to F.

In the case D where R3 includes an unsaturated carbon bond (one or morecarbon-carbon double bonds or carbon-carbon triple bonds), the number ofcyano group in R4 is one or larger. One reason for this is that, when R3includes the unsaturated carbon bond, a film resulting from the cyanocompound is easily formed intrinsically, and therefore, it is enoughthat at least one cyano group is present that contributes to reactivityof the cyano compound. The type of R3 in this case may be one of, forexample, an unsaturated hydrocarbon group, halogenated groups thereof,groups each obtained by bonding two or more of groups including theforegoing groups to one another, etc. R4 that includes the cyano groupmay include the unsaturated carbon bond or may not include theunsaturated carbon bond.

In the case E where R3 does not include the unsaturated carbon bond andR4 includes the unsaturated carbon bond, the number of cyano group in R4is one or larger. One reason for this is that, when R3 does not includethe unsaturated carbon bond but R4 includes the unsaturated carbon bond,a film resulting from the cyano compound is easily formed intrinsically,and therefore, it is enough that at least one cyano group is presentthat contributes to reactivity of the cyano compound. The type of R3 inthis case may be one of, for example, a saturated hydrocarbon group, anoxygen-containing hydrocarbon group, halogenated groups of the foregoinggroups, and groups each obtained by bonding two or more of groupsincluding the foregoing groups to one another, etc. The type of R4 thatincludes the cyano group and the unsaturated carbon bond will bedescribed later.

In the case F where R3 does not include the unsaturated carbon bond andR4 does not include the unsaturated carbon bond either, the number ofcyano group in R4 is two or larger. One reason for this is that, wheneither of R3 and R4 does not include the unsaturated carbon bond, a filmresulting from the cyano compound is less likely to be formedintrinsically, and therefore, two or more cyano groups are necessarythat contribute to reactivity of the cyano compound. The type of R3 inthis case may be one of, for example, a saturated hydrocarbon group, anoxygen-containing hydrocarbon group, halogenated groups of the foregoinggroups, and groups each obtained by bonding two or more of groupsincluding the foregoing groups to one another, etc. The type of R4 thatincludes the cyano group but does not include the unsaturated carbonbond will be described later.

Here, the details of R1 to R3 are as follows. The term “hydrocarbongroup” collectively refers to groups that are each configured of carbon(C) and hydrogen (H) and may be a straight-chain group or a branchedgroup that has one or more side chains. Out of the hydrocarbon groups,“unsaturated hydrocarbon group” refers to a hydrocarbon group that hasone or more unsaturated carbon bonds (carbon-carbon double bonds orcarbon-carbon triple bonds) and “saturated hydrocarbon group” refers toa hydrocarbon group that does not include the above-describedunsaturated carbon bond.

“Oxygen-containing hydrocarbon group” collectively refers to groups thatare each configured of carbon, hydrogen, and oxygen (O), and may be astraight-chain group or a branched group that has one or more sidechains.

The type of a halogen group in “halogenated group” is not particularlylimited. However, the type thereof may be, for example, one or more of afluorine group (—F), a chlorine group (—Cl), a bromine group (—Br), aniodine group (—I), etc., and, in particular, is preferably the fluorinegroup since a film resulting from the cyano compound is easily formedthereby.

“Group obtained by bonding two or more of the foregoing groups to oneanother” is a group in which two or more of the above-describedmonovalent groups such as a saturated hydrocarbon group are bonded toone another so as to be monovalent as a whole.

Specific examples of the saturated hydrocarbon group may include analkyl group, a cycloalkyl group, and groups each obtained by bonding twoor more of groups including the foregoing groups to one another. Inparticular, the carbon number of the alkyl group is preferably from 1 to12 both inclusive and the carbon number of the cycloalkyl group ispreferably from 3 to 18 both inclusive since superior solubility andsuperior compatibility are obtained thereby.

Specific examples of the unsaturated hydrocarbon group may include analkenyl group, an alkynyl group, an aryl group, and groups each obtainedby bonding two or more of groups including the foregoing groups to oneanother. In particular, the carbon numbers of the alkenyl group, of thealkynyl group, and of the aryl group are preferably from 2 to 12 bothinclusive, from 2 to 12 both inclusive, and from 6 to 18 both inclusive,respectively, since superior solubility and superior compatibility areobtained thereby.

Specific examples of the oxygen-containing saturated hydrocarbon groupmay include an alkoxy group and groups each obtained by bonding two ormore of groups including the foregoing group to one another. Inparticular, the carbon number of the alkoxy group is preferably from 1to 12 both inclusive since superior solubility and superiorcompatibility are obtained thereby.

Specific examples of the halogenated group may include a group obtainedby substituting, by a halogen group, each of part or all of hydrogengroups in the above-described alkyl group, cycloalkyl group, alkenylgroup, alkynyl group, aryl group, alkoxy group, or a group obtained bybonding two or more of groups including the foregoing groups to oneanother.

Specific examples of the group obtained by bonding two or more of groupsto one another may include a group (benzyl group) obtained by bonding analkyl group and an aryl group to each other.

More specifically, examples of the alkyl group may include, a methylgroup (—CH₃), an ethyl group (—C₂H₅), and a propyl group (—C₃H₇).Examples of the alkenyl group may include a vinyl group (—C₂H₃) and anallyl group (—C₃H₅). Examples of the alkynyl group may include anethynyl group (—C₂H₁). Examples of the aryl group may include a phenylgroup and a naphtyl group. Examples of the cycloalkyl group may includea cyclopropyl group, a cyclobutyl group, a cyclopentyl group, acyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Examplesof the alkoxy group may include a methoxy group (—OCH₃) and an ethoxygroup (—OC₂H₅). Examples of a halogenated group may include atrifluoromethyl group (—CF₃) and a pentafluoroethyl group (—C₂F₅).

It is to be noted that R1 to R3 may each be a derivative of theabove-described series of groups. The derivative is a group obtained byintroducing one or more substituent groups into the series of groups andthe substituent groups may be any type.

The type of the cyano-group-containing group is not particularly limitedas long as the cyano-group-containing group contains one or more cyanogroups and the cyano groups are each bonded to an oxygen atom at aterminal of a —O—C(═O)—O— bond or a —C(═O)—O— bond with a carbon atom inbetween. One reason for this is that, when the above-describedconditions are satisfied, the above-described advantages are obtainedindependently of the chemical structure of the cyano-group-containinggroup.

Specific examples of the cyano-group-containing group may include agroup obtained by substituting each of part or all of hydrogen groups ina saturated hydrocarbon group by a cyano group and a group obtained bysubstituting each of part or all of hydrogen groups in an unsaturatedhydrocarbon group by a cyano group. In particular, the above-describedsaturated hydrocarbon group is preferably an alkyl group and theabove-described unsaturated hydrocarbon group is preferably an arylgroup. Further, the carbon number of the alkyl group is preferably from1 to 12 both inclusive and the carbon number of the aryl group ispreferably from 6 to 18 both inclusive since superior solubility andsuperior compatibility are obtained thereby. It is to be noted that theciano-group-containing group may be a group other than those describedabove.

Specific examples of the cyano compound may be the followings. Examplesof the carbonate-ester type cyano compound may include compoundsrepresented by the following Formula (1-1) to Formula (1-25). Further,examples of the ester type cyano compound may include compoundsrepresented by the following Formula (2-1) to Formula (2-21). It is tobe noted that the cyano compound may be other compound that satisfiesthe conditions shown in Formula (1) or (2).

A content of the cyano compound in the electrolytic solution is notparticularly limited. However, in particular, the content of the cyanocompound is preferably from 0.01 wt % to 20 wt % both inclusive and ismore preferably from 0.1 wt % to 10 wt % both inclusive since a highereffect is obtained thereby.

[Non-Cyano Compound]

The electrolytic solution preferably includes a non-cyano compoundtogether with the cyano compound. The non-cyano compound may include,for example, one or more of a compound represented by the followingFormula (3), a compound represented by the following Formula (4), acompound represented by the following Formula (5), a compoundrepresented by the following Formula (6), and a compound represented bythe following Formula (7), since chemical stability of the electrolyticsolution is further improved, and therefore, a decomposition reaction ofthe electrolytic solution is further suppressed thereby.

(R11 and R13 are each one of a monovalent hydrocarbon group, amonovalent oxygen-containing hydrocarbon group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another. R12 is one of a divalenthydrocarbon group and halogenated groups thereof.)

(R14 and R16 are each one of a monovalent hydrocarbon group, amonovalent oxygen-containing hydrocarbon group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another. R15 is one of a divalenthydrocarbon group and halogenated groups thereof. n is an integer thatis 1 or larger.)

(R17 and R19 are each one of a monovalent hydrocarbon group, amonovalent oxygen-containing hydrocarbon group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another. R18 is one of a divalenthydrocarbon group and halogenated groups thereof.)

LiPF₂O₂  (6)

Li₂PFO₃  (7)

The compound represented by Formula (3) is a dicarbonate ester compoundthat has carbonate ester groups (—O—C(═O)—O—R11 and —O—C(═O)—O—R13) atboth terminals thereof. R11 and R13 may be the same type of group or maybe different types of group.

The type of each of R11 and R13 is not particularly limited as long asthe type thereof is one of a monovalent hydrocarbon group, a monovalentoxygen-containing hydrocarbon group, halogenated groups of the foregoinggroups, and groups each obtained by bonding two or more of the foregoinggroups to one another. The terms “Hydrocarbon group”, “oxygen-containinghydrocarbon group”, “halogenated group” and “group obtained by bondingtwo or more of the foregoing groups to one another” similarly refer tothose described for the cyano compound. One reason for this is that theabove-described advantages are obtained independently of the types ofR11 and R13 since the dicarbonate ester compound includes theabove-described carbonate ester group.

Examples of the monovalent hydrocarbon group may include an alkyl groupwith carbon number from 1 to 12 both inclusive, an alkenyl group withcarbon number from 2 to 12 both inclusive, an alkynyl group with carbonnumber from 2 to 12 both inclusive, an aryl group with carbon numberfrom 6 to 18 both inclusive, a cycloalkyl group with carbon number from3 to 18 both inclusive, and an alkoxy group with carbon number from 1 to12 both inclusive, and groups each obtained by bonding two or more ofthe foregoing groups to one another, since the above-describedadvantages are obtained while securing, for example, solubility,compatibility, and the like of the dicarbonate ester compound. It is tobe noted that the details of the above-described alkyl group, etc. aresimilar to those described for the cyano compound.

The type of R12 is not particularly limited as long as the type thereofis one of a divalent hydrocarbon group and halogenated groups thereof asdescribed above. The term “halogenated group” similarly refers to thatdescribed for the cyano compound since the above-described advantagesare obtained independently of the type of R12 based on a reason similarto that described above for R11 and R13.

Examples of the divalent hydrocarbon group may include an alkylene groupwith carbon number from 1 to 12 both inclusive, an alkenylene group withcarbon number from 2 to 12 both inclusive, an alkynylene group withcarbon number from 2 to 12 both inclusive, an arylene group with carbonnumber from 6 to 18 both inclusive, a cycloalkylene group with carbonnumber from 3 to 18 both inclusive, groups each obtained by bonding twoor more of the foregoing groups to one another, and groups each obtainedby bonding one or more of the foregoing groups and an ether bond (—O—)to one another since the above-described advantages are obtained whilesecuring, for example, solubility, compatibility, and the like of thedicarbonate ester compound.

The term “group obtained by bonding two or more of the foregoing groupsto one another” refers to a group in which two or more of theabove-described groups such as an alkylene group are bonded to oneanother so as to be divalent as a whole and may be, for example, a groupin which an alkylene group and a arylene group is bonded to each other.The group in which an alkylene group and a arylene group is bonded toeach other may be a group in which one arylene group and one alkylenegroup are bonded to each other or a group (aralkylene group) in whichtwo alkylene groups are bonded to each other with an arylene group inbetween.

“Group obtained by bonding one or more of the foregoing groups and anether bond (—O—) to one another” is a group in which one or more of theabove-described groups such as an alkylene group and one or more etherbonds are bonded to one another so as to be divalent as a whole.Examples thereof may include a group in which an alkylene group and anether bond is bonded to each other. The group in which an alkylene groupand an ether bond is bonded to each other may be a group in which onealkylene group and one ether bond are bonded to each other, may be agroup in which two alkylene groups are bonded to each other with oneether bond in between, or may be a group in which a plurality ofalkylene groups are alternately bonded to one another with ether bondsin between.

Specific examples of R12 may include straight-chain alkylene groupsrepresented by the following Formula (3-13) to Formula (3-19), branchedalkylene groups represented by Formula (3-20) to Formula (3-28), arylenegroups represented by Formula (3-29) to (3-31), and benzylidene groupsrepresented by Formula (3-32) to (3-34).

It is to be noted that, as the divalent group in which an alkylene groupand an ether bond are bonded to each other is preferably a group inwhich two or more alkylene groups are alternately combined to oneanother with ether bonds in between and the both terminals are carbonatoms. The carbon number of such a group is preferably from 4 to 12 bothinclusive since superior solubility and superior compatibility areobtained thereby. It is to be noted that the number of ether bond may beany number.

Specific examples of R12 in this case may include divalent groupsrepresented by the following Formula (3-35) to Formula (3-47). Further,when the divalent groups represented by Formula (3-35) to Formula (3-47)are fluorinated, specific examples of R12 may be, for example, groupsrepresented by Formula (3-48) to Formula (3-56), and in particular,groups represented by Formula (3-40) to Formula (3-42) are preferable.

—CH₂—O—CH₂—  (3-35)

—CH₂O—CH₂₂  (3-36)

—CH₂O—CH₂₃  (3-37)

—CH₂O—CH₂₄  (3-38)

—CH₂O—CH₂₅  (3-39)

—CH₂—CH₂—O—CH₂—CH₂—  (3-40)

—CH₂—CH₂O—CH₂—CH₂₂  (3-41)

—CH₂—CH₂O—CH₂—CH₂₃  (3-42)

—CH₂—CH₂O—CH₂—CH₂₄  (3-43)

—CH₂—CH₂O—CH₂—CH₂₅  (3-44)

—CH₂—CH₂—CH₂—O—CH₂—CH₂—CH₂—  (3-45)

—CH₂—CH₂—CH₂O—CH₂—CH₂—CH₂₂  (3-46)

—CH₂—CH₂—CH₂O—CH₂—CH₂—CH₂₃  (3-47)

—CF₂—O—CF₂—  (3-48)

—CF₂O—CF₂₂  (3-49)

—CF₂O—CF₂₃  (3-50)

—CF₂—CF₂—O—CF₂—CF₂—  (3-51)

—CF₂—CF₂O—CF₂—CF₂₂  (3-52)

—CF₂—CF₂O—CF₂—CF₂₃  (3-53)

—CH₂—CF₂—O—CF₂—CH₂—  (3-54)

—CH₂—CF₂—O—CF₂—CF₂—O—CF₂—CH₂—  (3-55)

—CH₂—CF₂O—CF₂—CF₂₂O—CF₂—CH₂—  (3-56)

Molecular weight of the dicarbonate ester compound is not particularlylimited, however, in particular, is preferably from 200 to 800 bothinclusive, more preferably from 200 to 600 both inclusive, and furthermore preferably from 200 to 450 both inclusive since superior solubilityand superior compatibility are obtained thereby.

Specific examples of the dicarbonate ester compound may includecompounds represented by the following Formula (3-1) to Formula (3-12)since sufficient solubility and sufficient compatibility are obtainedand chemical stability of the electrolyte solution is sufficientlyimproved. It is to be noted that the dicarbonate ester compound may beother compounds that satisfy the conditions of the chemical formulashown in Formula (3).

The compound represented by Formula (4) is a dicarboxylic acid compoundthat has carboxylic acid groups (—O—C(═O)—R14 and —O—C(═O)—R16) at bothterminals thereof. The value of n is not particularly limited as long asthe value is an integer of 1 or larger. R14 and R16 may the same type ofgroup or may be different types of group. The details of R14 to R16 maybe, for example, similar to those of the above-described R11 to R13.

Molecular weight of the dicarboxylic acid compound is not particularlylimited. However, in particular, the molecular weight thereof ispreferably from 162 to 1000 both inclusive, more preferably from 162 to500 both inclusive, and further more preferably from 162 to 300 bothinclusive since superior solubility and superior compatibility areobtained thereby.

Specific examples of the dicarboxylic acid compound include compoundsrepresented by the following Formula (4-1) to Formula (4-17) sincesufficient solubility and sufficient compatibility are obtained therebyand chemical stability of the electrolytic solution is sufficientlyimproved thereby. It is to be noted that the dicarboxylic acid compoundmay be other compounds that satisfy the conditions of the chemicalformula shown in Formula (4).

The compound represented by Formula (5) is a disulfonate compound thathas sulfonate groups (—O—S(═O)₂—R17 and —O—S(═O)₂—R19) at both terminalsthereof. R17 and R19 may be the same type of group or may be differenttypes of group. The details of R17 to R19 may be, for example, similarto those of R11 to R13, respectively.

Molecular weight of the disulfonate compound is not particularlylimited. However, in particular, the molecular weight thereof ispreferably from 200 to 800 both inclusive, more preferably from 200 to600 both inclusive, and further more preferably from 200 to 450 bothinclusive since superior solubility and superior compatibility areobtained thereby.

Specific examples of the disulfonate may include compounds representedby the following Formula (5-1) to Formula (5-9) since sufficientsolubility and sufficient compatibility are obtained thereby andchemical stability of the electrolytic solution is sufficiently improvedthereby. However, the disulfonate compound may be other compounds thatsatisfy conditions of the chemical formula shown in Formula (5).

The compound represented by Formula (6) is lithium difluorophosphate andthe compound represented by Formula (7) is lithium monofluorophosphate.

A content of the non-cyano compound in the electrolytic solution is notparticularly limited. However, in particular, the content of thenon-cyano compound is preferably from 0.001 wt % to 2 wt % bothinclusive since a higher effect is obtained thereby.

[Solvent]

The solvent includes one or more of non-aqueous solvents (excluding theabove-described cyano compounds and non-cyano compounds) such as organicsolvents.

Examples of the non-aqueous solvent include cyclic ester carbonate,chain ester carbonate, lactone, chain carboxylic ester, and nitrile,since, for example, superior battery capacity, superior cyclecharacteristics, superior conservation characteristics, and the like areobtained. Examples of the cyclic ester carbonate include ethylenecarbonate, propylene carbonate, and butylene carbonate. Examples of thechain ester carbonate include dimethyl carbonate, diethyl carbonate,ethyl methyl carbonate, and methyl propyl carbonate. Examples of thelactone include γ-butyrolactone and γ-valerolactone. Examples of thecarboxylic ester include methyl acetate, ethyl acetate, methylpropionate, ethyl propionate, methyl butyrate, methyl isobutyrate,methyl trimethylacetate, and ethyl trimethylacetate. Examples of thenitrile include acetonitrile, glutaronitrile, adiponitrile,methoxyacetonitrile, and 3-methoxypropionitrile.

In addition thereto, examples of the non-aqueous solvent include1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran,tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane,1,4-dioxane, N,N-dimethylformamide, N-methylpyrrolidinone,N-methyloxazolidinone, N,N′-dimethylimidazolidinone, nitromethane,nitroethane, sulfolane, trimethyl phosphate, and dimethyl sulfoxide,since similar advantages are obtained thereby.

In particular, the solvent is preferably one or more of ethylenecarbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate,and ethyl methyl carbonate, since, for example, a superior batterycapacity, superior cycle characteristics, superior conservationcharacteristics, and the like are obtained thereby. In this case, acombination of a high viscosity (high dielectric constant) solvent (forexample, specific dielectric constant ∈≧30) such as ethylene carbonateand propylene carbonate and a low viscosity solvent (for example,viscosity≦1 mPa·s) such as dimethyl carbonate, ethyl methyl carbonate,and diethyl carbonate is more preferable since the dissociationproperties of the electrolyte salt and ion mobility are improvedthereby.

In particular, the solvent preferably includes one or more ofunsaturated cyclic ester carbonates since a stable protective film isthereby formed mainly on the surface of the anode 22 at the time ofcharge and discharge, and therefore a decomposition reaction of theelectrolytic solution is suppressed. The unsaturated cyclic estercarbonate is a cyclic ester carbonate that has one or more unsaturatedbonds (carbon-carbon double bonds). More specifically, the unsaturatedcyclic ester carbonate is one of vinylene-carbonate-based compoundsrepresented by the following Formula (8), vinyl-ethylene-carbonate-basedcompounds represented by the following Formula (9), andmethylene-ethylene-carbonate-based compounds represented by thefollowing Formula (10). R21 and R22 may the same type of group or may bedifferent types of group. This is similarly applicable to R23 to R26. Acontent of the unsaturated cyclic ester carbonate in the solvent is notparticularly limited. However, the content thereof may be, for example,from 0.01 wt % to 10 wt % both inclusive. It is to be noted thatspecific examples of the unsaturated cyclic ester carbonate is notlimited to the compounds described below.

(R21 and R22 are each one of a hydrogen group and an alkyl group.)

(R23 to R26 are each one of a hydrogen group, an alkyl group, a vinylgroup, and an allyl group. One or more of R23 to R26 are each one of avinyl group and an allyl group.)

(R27 is an alkylene group.)

Examples of the vinylene-carbonate based compound may include vinylenecarbonate (1,3-dioxole-2-one), methylvinylene carbonate(4-methyl-1,3-dioxole-2-one), ethylvinylene carbonate(4-ethyl-1,3-dioxole-2-one), 4,5-dimethyl-1,3-dioxole-2-one,4,5-diethyl-1,3-dioxole-2-one, 4-fluoro-1,3-dioxole-2-one, and4-trifluoromethyl-1,3-dioxole-2-one. In particular, vinylene carbonateis preferable since vinylene carbonate is easily obtained and provides ahigh effect.

Examples of vinyl-ethylene-carbonate-based compound may include vinylethylene carbonate (4-vinyl-1,3-dioxolan-2-one),4-methyl-4-vinyl-1,3-dioxolan-2-one, 4-ethyl-4-vinyl-1,3-dioxolan-2-one,4-n-propyl-4-vinyl-1,3-dioxolan-2-one,5-methyl-4-vinyl-1,3-dioxolan-2-one, 4,4-divinyl-1,3-dioxolan-2-one, and4,5-divinyl-1,3-dioxolan-2-one. In particular, vinyl ethylene carbonateis preferable since vinyl ethylene carbonate is easily obtained andprovides a high effect. It goes without saying that all of R32 to R35may be vinyl groups or may be allyl groups. Alternatively, some of R32to R35 may be vinyl groups and others thereof may be allyl groups.

Examples of methylene-ethylene-carbonate-based compound may includemethylene ethylene carbonate (4-methylene-1,3-dioxolane-2-one),4,4-dimethyl-5-methylene-1,3-dioxolane-2-one, and4,4-diethyl-5-methylene-1,3-dioxolane-2-one. Themethylene-ethylene-carbonate-based compound is not limited to a compoundthat has one methylene group as shown in Formula (10) and may be acompound that has two methylene groups.

It is to be noted that the unsaturated cyclic ester carbonate may be,for example, catechol carbonate that has a benzene ring or the like.

Further, the solvent preferably includes one or more of halogenatedester carbonates since a stable protective film is formed mainly on thesurface of the anode 22 at the time of charge and discharge, andtherefore a decomposition reaction of the electrolytic solution issuppressed. The halogenated ester carbonate is a cyclic or chain estercarbonate that includes one or more halogens as constituent elements.More specifically, the cyclic halogenated ester carbonate is representedby the following Formula (11) and the chain halogenated ester carbonateis represented by the following Formula (12). R28 to R31 may be the sametype of group or may be different types of group. Alternatively, part ofR28 to R31 may be the same group. This is similarly applicable to R32 toR37. A content of the halogenated ester carbonate in the solvent is notparticularly limited. However, the content of the halogenated estercarbonate may be, for example, from 0.01 wt % to 50 wt % both inclusive.It is to be noted that specific examples of the halogenated estercarbonate are not limited to compounds described below.

(R28 to R31 are each one of a hydrogen group, a halogen group, an alkylgroup, and a halogenated alkyl group. One or more of R28 to R31 are eachone of the halogen group and the halogenated alkyl group.)

(R32 to R37 are each one of a hydrogen group, a halogen group, an alkylgroup, and a halogenated alkyl group. One or more of R32 to R37 are eachone of the halogen group and the halogenated alkyl group.)

The type of the halogen is not particularly limited. However, inparticular, the halogen is preferably one of fluorine, chlorine,bromine, and iodine, and is more preferably fluorine since a highereffect is obtained thereby compared to other halogens. It is to be notedthat the number of the halogen is preferably two than one, and may bethree or more. One reason for this is that the ability to form aprotective film is improved and a more rigid and more stable protectivefilm is formed. Therefore, the decomposition reaction of theelectrolytic solution is further suppressed.

Examples of the halogenated cyclic ester carbonate may include compoundsrepresented by the following Formula (1-1) to Formula (11-21). Theexamples of the halogenated cyclic ester carbonate may include geometricisomers thereof. In particular, 4-fluoro-1,3-dioxolan-2-one representedby Formula (11-1) and 4,5-difluoro-1,3-dioxolan-2-one represented byFormula (11-3) are preferable, and the latter compound is morepreferable. Also, as 4,5-difluoro-1,3-dioxolan-2-one, a trans isomerthereof is more preferable than a cis isomer thereof since the transisomer thereof is easily obtained and provides a high effect. On theother hand, examples of the halogenated chain ester carbonate mayinclude fluoromethyl methyl carbonate, bis(fluoromethyl) carbonate, anddifluoromethyl methyl carbonate.

Further, the solvent preferably includes sultone (cyclic estersulfonate) since chemical stability of the electrolytic solution isfurther improved. Examples of the sultone may include propane sultoneand propene sultone. A content of the sultone in the solvent is notparticularly limited. However, the content of the sultone may be, forexample, from 0.5 wt % to 5 wt % both inclusive. It is to be noted thatspecific examples of the sultone are not limited to the compoundsdescribed above.

Further, the solvent preferably includes an acid anhydride sincechemical stability of the electrolytic solution is further improvedthereby. Examples of the acid anhydride include carboxylic anhydride,disulfonic anhydride, and carboxylic acid sulfonic acid anhydride.Examples of the carboxylic anhydride may include succinic anhydride,glutaric anhydride, and maleic anhydride. Examples of the disulfonicanhydride may include ethane disulfonic anhydride and propane disulfonicanhydride. Examples of the carboxylic acid sulfonic acid anhydride mayinclude sulfobenzoic anhydride, sulfopropionic anhydride, andsulfobutyric anhydride. A content of the acid anhydride in the solventis not particularly limited. However, the content thereof may be, forexample, from 0.5 wt % to 5 wt % both inclusive. It is to be noted thatspecific examples of the acid anhydrides are not limited to theabove-described compounds.

[Electrolyte Salt]

The electrolyte salt may include, for example, one or more of salts suchas lithium salts. It is to be noted that the electrolyte salt mayinclude, for example, salts other than lithium salts. “Salts other thanlithium salts” may refer, for example, to salts such as light metalsalts other than lithium salts.

Examples of the lithium salts may include lithium hexafluorophosphate(LiPF₆), lithium tetrafluoroborate (LiBF₄), lithium perchlorate(LiClO₄), lithium hexafluoroarsenate (LiAsF₆), lithium tetraphenylborate(LiB(C₆H₅)₄), lithium methanesulfonate (LiCH₃SO₃), lithiumtrifluoromethanesulfonate (LiCF₃SO₃), lithium tetrachloroaluminate(LiAlCl₄), dilithium hexafluorosilicate (Li₂SiF₆), lithium chloride(LiCl), and lithium bromide (LiBr), since, for example, superior batterycharacteristics, superior cycle characteristics, superior conservationcharacteristics, and the like are obtained thereby. It is to be notedthat specific examples of the lithium salt are not limited to theabove-described compounds.

In particular, one or more of LiPF₆, LiBF₄, LiClO₄, and LiAsF₆ arepreferable, and LiPF₆ is more preferable, since the internal pressure isthereby lowered and a higher effect is obtained.

In particular, the electrolyte salt preferably includes one or more ofcompounds represented by the following Formula (13), compoundsrepresented by the following Formula (14), and compounds represented bythe following Formula (15) since a higher effect is thereby obtained. Itis to be noted that R41 and R43 may be the same type of group, or may bedifferent types of group. This is similarly applicable to R51 to R53,and to R61 and R62. It is to be noted that specific examples of thecompounds represented by Formula (13) to Formula (15) are not limited tocompounds described below.

(X41 is one of Group 1 elements and Group 2 elements in the long-periodperiodic table and aluminum. M41 is one of transition metals and Group13 elements, Group 14 elements, and Group 15 elements in the long-periodperiodic table. R41 is a halogen group. Y41 is one of —C(═O)—R42-C(═O)—,—C(═O)—CR43₂-, and —C(═O)—C(═O)—. It is to be noted that R42 is one ofan alkylene group, a halogenated alkylene group, an arylene group, and ahalogenated arylene group. R43 is one of an alkyl group, a halogenatedalkyl group, an aryl group, and a halogenated aryl group. It is to benoted that a4 is an integer from 1 to 4, b4 is an integer of one of 0,2, and 4, and c4, d4, m4, and n4 are each an integer from 1 to 3.)

(X51 is one of Group 1 elements and Group 2 elements in the long-periodperiodic table. M51 is one of transition metals, and Group 13 elements,Group 14 elements, and Group 15 elements in the long-period periodictable. Y51 is one of —C(═O)—(CR51₂)_(b5)—C(═O)—,—R53₂C—(CR52₂)_(c5)—C(═O)—, —R53₂C—(CR52₂)_(c5)—CR53₂—,—R53₂C—(CR52₂)_(c5)—S(═O)₂—, —S(═O)₂—(CR52₂)_(d5)—S(═O)₂—, and—C(═O)—(CR52₂)_(d5)—S(═O)₂—. It is to be noted that R51s and R53s areeach one of a hydrogen group, an alkyl group, a halogen group, and ahalogenated alkyl group, and one or more of R51s and one or more of R53sare each one of a halogen group and a halogenated alkyl group. R52s areeach one of a hydrogen group, an alkyl group, a halogen group, and ahalogenated alkyl group. It is to be noted that a5, e5, and n5 are eachan integer of 1 or 2, b5 and d5 are each an integer from 1 to 4, c5 isan integer from 0 to 4, and f5 and m5 are each an integer from 1 to 3.)

(X61 is one of Group 1 elements and Group 2 elements in the long-periodperiodic table. M61 is one of transition metals and Group 13 elements,Group 14 elements, and Group 15 elements in the long-period periodictable. Rfs are each one of a fluorinated alkyl group and a fluorinatedaryl group, and carbon number of any of Rfs is from 1 to 10 bothinclusive. Y61 is one of —C(═O)—(CR61₂)_(d6)—C(═O)—,—R62₂C—(CR61₂)_(d6)—C(═O)—, —R62₂C—(CR61₂)_(e6)—CR62₂—,—R62₂C—(CR61₂)_(d6)—S(═O)₂—, —S(═O)₂—(CR61₂)_(e6)—S(═O)₂—, and—C(═O)—(CR61₂)_(e6)—S(═O)₂—. It is to be noted that R61 is one of ahydrogen group, an alkyl group, a halogen group, and a halogenated alkylgroup. R62s are each one of a hydrogen group, an alkyl group, a halogengroup, and a halogenated alkyl group, and one or more of R62s are eachone of a halogen group and a halogenated alkyl group. It is to be notedthat a6, f6, and n6 are each an integer of 1 or 2, b6, c6, and e6 areeach an integer from 1 to 4, d6 is an integer from 0 to 4, and g6 and m6are each an integer from 1 to 3.)

It is to be noted that Group 1 elements include H, Li, Na, K, Rb, Cs,and Fr. Group 2 elements include Be, Mg, Ca, Sr, Ba, and Ra. Group 13elements include B, Al, Ga, In, and Tl. Group 14 elements include C, Si,Ge, Sn, and Pb. Group 15 elements include N, P, As, Sb, and Bi.

Examples of the compound represented by Formula (13) may includecompounds represented by Formula (13-1) to Formula (13-6). Examples ofthe compound represented by Formula (14) may include compoundsrepresented by Formula (14-1) to Formula (14-8). Examples of thecompound represented by Formula (15) may include a compound representedby Formula (15-1).

Further, the electrolyte salt preferably includes one or more of chainimide compounds represented by the following Formula (16), cyclic imidecompounds represented by the following Formula (17), and chain methidecompounds represented by the following Formula (18), since a highereffect is obtained thereby. It is to be noted that m and n may be thesame value, or may be different values. This is similarly applicable top, q, and r. It is to be noted that specific examples of the compoundsrepresented by Formula (16) to Formula (18) are not limited to compoundsdescribed below.

LiN(C_(m)F_(2m+1)SO₂)(C_(n)F_(2n+1) SO₂)  (16)

(m and n are each an integer of 1 or larger.)

(R71 is a straight-chain or branched perfluoroalkylene group with carbonnumber from 2 to 4 both inclusive.)

LiC(C_(p)F_(2p+1)SO₂)(C_(q)F_(2q+1)SO₂)(CrF_(2r+1)SO₂)  (18)

(p, q, and r are each an integer of 1 or larger.)

Examples of the chain imide compound may includebis(trifluoromethanesulfonyl)imide lithium (LiN(CF₃SO₂)₂),bis(pentafluoroethanesulfonyl)imide lithium (LiN(C₂F₅SO₂)₂),(trifluoromethanesulfonyl) (pentafluoroethanesulfonyl) imide lithium(LiN(CF₃SO₂)(C₂F₅SO₂)),(trifluoromethanesulfonyl)(heptafluoropropanesulfonyl) imide lithium(LiN(CF₃SO₂)(C₃F₇SO₂)), and(trifluoromethanesulfonyl)(nonafluorobutanesulfonyl) imide lithium(LiN(CF₃SO₂)(C₄F₉SO₂)).

Examples of the cyclic imide compound may include compounds representedby Formula (17-1) to (17-4).

Examples of the chain methide compound may include lithiumtris(trifluoromethanesulfonyl)methide (LiC(CF₃SO₂)₃).

A content of the electrolyte salt is not particularly limited. However,in particular, the content thereof is preferably from 0.3 mol/kg to 3.0mol/kg both inclusive with respect to the non-aqueous solvent since highion conductivity is obtained thereby.

[Operation of Secondary Battery]

The secondary battery may operates as follows, for example. Lithium ionsextracted from the cathode 21 may be inserted in the anode 22 throughthe electrolytic solution at the time of charge. On the other hand,lithium ions extracted from the anode 22 may be inserted in the cathode21 through the electrolytic solution at the time of discharge.

[Method of Manufacturing Secondary Battery]

The secondary battery may be manufactured, for example, by the followingprocedure.

First, the cathode 21 is fabricated. A cathode active material is mixedwith, for example, a cathode binder and the like where appropriate toprepare a cathode mixture. Subsequently, the cathode mixture isdispersed, for example, in an organic solvent and/or the like to obtainpaste cathode mixture slurry. Subsequently, both surfaces of the cathodecurrent collector 21A are coated with the cathode mixture slurry, andthe resultant is dried. Thus, the cathode active material layer 21B isformed. Subsequently, the cathode active material layer 21B iscompression-molded with the use of, for example, a roll pressing machineand/or the like where appropriate. In this case, the cathode activematerial layer 21B may be compression-molded while being heated andcompression-molding may be repeated several times.

Further, the anode 22 is fabricated by procedures similar to thosedescribed above for the cathode 21. An anode mixture in which the anodeactive material, and, where appropriate, the anode binder and/or thelike are mixed is dispersed in an organic solvent and/or the like toobtain paste anode mixture slurry. Subsequently, both surfaces of theanode current collector 22A are coated with the anode mixture slurry,and the resultant is dried. Thus, the anode active material layer 22B isformed. Thereafter, the anode active material layer 22B iscompression-molded where appropriate.

Further, the electrolyte salt is dispersed in the solvent, and then, acyano compound is added thereto to prepare the electrolytic solution. Inthis case, a non-cyano compound may be added thereto where appropriate.

Finally, the secondary battery is assembled with the cathode 21 and theanode 22. The cathode lead 25 is attached to the cathode currentcollector 21A, for example, by a welding method and/or the like and theanode lead 26 is similarly attached to the anode current collector 22A,for example, by a welding method and/or the like. Subsequently, thecathode 21 and the anode 22 are laminated with the separator 23 inbetween and are spirally wound. Thus, the spirally wound electrode body20 is fabricated. Thereafter, the center pin 24 is inserted in a centerhollow of the spirally wound electrode body 20. Subsequently, thespirally wound electrode body 20 is sandwiched between the pair ofinsulating plates 12 and 13, and is contained in the battery can 11. Inthis case, the end tip of the cathode lead 25 is attached to the safetyvalve mechanism 15, for example, by a welding method and/or the like andthe end tip of the anode lead 26 is similarly attached to the batterycan 11, for example, by a welding method and/or the like. Subsequently,the electrolytic solution is injected into the battery can 11, and theseparator 23 is impregnated with the electrolytic solution.Subsequently, the battery cover 14, the safety valve mechanism 15, andthe PTC device 16 are fixed by being swaged with the gasket 17 at theopen end of the battery can 11.

[Functions and Effects of Secondary Battery]

According to the present cylindrical type secondary battery, theelectrolytic solution includes the above-described cyano compound. Inthis case, a decomposition reaction of the electrolytic solution issuppressed even under severe temperature environment, in particular,under high temperature, compared to in the case where the electrolyticsolution does not include the cyano compound and to in the case wherethe electrolytic solution includes other cyano compound. Examples of“other cyano compound” may include a carbonate-ester type cyano compoundrepresented by the following Formula (18-1) and an ester type cyanocompound represented by the following Formula (18-2). In the compoundrepresented by Formula (18-1), R1 is a saturated hydrocarbon group(methyl group) and R2 is a cyano-group-containing group in Formula (1).Irrespective of this, the number of cyano group in R2 is one. In thecompound represented by Formula (18-2), R3 is a saturated hydrocarbongroup (methyl group) in Formula (2). Irrespective of this, the number ofcyano group in R4 is one. Therefore, even when the secondary battery ischarged and discharged or is stored under severe temperatureenvironment, the electrolytic solution is less likely to be decomposed.Therefore, superior battery characteristics are obtained.

In particular, when the content of the cyano compound in theelectrolytic solution is from 0.01 wt % to 20 wt % both inclusive, ahigher effect is obtained.

Further, when the electrolytic solution includes the non-cyano compound,a higher effect is obtained. In this case, when the content of thenon-cyano compound in the electrolytic solution is from 0.001 wt % to 2wt % both inclusive, a further higher effect is obtained.

[1-2. Lithium Ion Secondary Battery (Laminated Film Type)]

FIG. 3 illustrates an exploded perspective configuration of anothersecondary battery according to the present embodiment. FIG. 4illustrates an enlarged cross section taken along a line IV-IV of aspirally wound electrode body 30 illustrated in FIG. 3. The elements ofthe cylindrical type secondary battery that have already been describedwill be used as necessary in the following description.

[General Configuration of Secondary Battery]

The secondary battery described herein is a so-called laminated filmtype lithium ion secondary battery. In the secondary battery, forexample, the spirally wound electrode body 30 may be contained in afilm-like outer package member 40. The spirally wound electrode body 30includes a cathode 33 and an anode 34 that are laminated with aseparator 35 and an electrolyte layer 36 in between, which is spirallywound. A cathode lead 31 is attached to the cathode 33, and an anodelead 32 is attached to the anode 34. The outermost periphery of thespirally wound electrode body 30 is protected by a protective tape 37.

The cathode lead 31 and the anode lead 32 may be, for example, led outfrom inside to outside of the outer package member 40 in the samedirection. The cathode lead 31 may be formed, for example, of anelectrically-conductive material such as aluminum, and the anode lead 32may be formed, for example, of an electrically-conducive material suchas copper, nickel, and stainless steel. These electrically-conductivematerials may be in the shape of, for example, a thin plate or mesh.

The outer package member 40 may be, for example, a laminated film inwhich a fusion bonding layer, a metal layer, and a surface protectivelayer are laminated in this order. The outer package member 40 mayformed, for example, by overlaying two laminated films so that thefusion bonding layer faces the spirally wound electrode body 30, andthen bonding the respective outer edges of the fusion bonding layers toeach other. It is to be noted that the two laminated film may beattached to each other, for example, with an adhesive agent and/or thelike in between. Examples of the fusion bonding layer include a filmmade of a material such as polyethylene and polypropylene. Examples ofthe metal layer include an aluminum foil. Examples of the surfaceprotective layer include a film made of a material such as nylon andpolyethylene terephthalate.

In particular, the outer package member 40 is preferably an aluminumlaminated film in which a polyethylene film, an aluminum foil, and anylon film are laminated in this order. It is to be noted that the outerpackage member 40 may be a laminated film that has other laminatedstructure, a polymer film such as a polypropylene film, or a metal film.

For example, an adhesive film 41 may be inserted between the outerpackage member 40 and the cathode lead 31 and between the outer packagemember 40 and the anode lead 32 to prevent outside air intrusion. Theadhesive film 41 is formed of a material that has adhesioncharacteristics with respect to the cathode lead 31 and to the anodelead 32. Examples of such an adhesive material include a polyolefinresin, and more specifically, a material such as polyethylene,polypropylene, modified polyethylene, and modified polypropylene.

The cathode 33 may include, for example, a cathode current collector 33Aand a cathode active material layer 33B that is provided on one or bothsurfaces of the cathode current collector 33A. The anode 34 may include,for example, an anode current collector 34A and an anode active materiallayer 34B that is provided on one or both surfaces of the anode currentcollector 34A. The configurations of the cathode current collector 33A,the cathode active material layer 33B, the anode current collector 34A,and the anode active material layer 34B are similar to those of thecathode current collector 21A, the cathode active material layer 21B,the anode current collector 22A, and the anode active material layer22B, respectively. Further, the configuration of the separator 35 issimilar to that of the separator 23.

The electrolyte layer 36 includes an electrolytic solution that is heldby a polymer compound, and is a so-called gel electrolyte, since highion conductivity (for example, 1 mS/cm or more at room temperature) isobtained and liquid leakage of the electrolytic solution is prevented.The electrolyte layer 36 may contain other materials such as an additivewhere appropriate.

Examples of the polymer compound may include one or more ofpolyacrylonitrile, polyvinylidene fluoride, polytetrafluoroethylene,polyhexafluoropropylene, polyethylene oxide, polypropylene oxide,polyphosphazene, polysiloxane, polyvinyl fluoride, polyvinyl acetate,polyvinyl alcohol, polymethacrylic acid methyl, polyacrylic acid,polymethacrylic acid, styrene-butadiene rubber, nitrile-butadienerubber, polystyrene, polycarbonate, and a copolymer of vinylidenefluoride and hexafluoro propylene. In particular, polyvinylidenefluoride or the copolymer of vinylidene fluoride and hexafluoropropylene is preferable, and polyvinylidene fluoride is more preferable,since such polymer compounds are electrochemically stable.

The composition of the electrolytic solution is similar to that of thecylindrical type secondary battery and the electrolytic solution thereofincludes the above-described cyano compound. It is to be noted that, inthe electrolyte layer 36 that is a gel electrolyte, “solvent” of theelectrolytic solution refers to a wide concept that includes not only aliquid solvent but also a material that has ion conductivity capable ofdissociating electrolyte salts. Therefore, when a polymer compound thathas ion conductivity is used, the polymer compound is also included inthe solvent.

It is to be noted that the electrolytic solution may be used as it isinstead of the gel electrolyte layer 36. In this case, the separator 35is impregnated with the electrolytic solution.

[Operation of Secondary Battery]

The secondary battery may operates as follows, for example. Lithium ionsextracted from the cathode 33 may be inserted in the anode 34 throughthe electrolyte layer 36 at the time of charge. On the other hand,lithium ions extracted from the anode 34 may be inserted in the cathode33 through the electrolyte layer 36 at the time of discharge.

[Method of Manufacturing Secondary Battery]

The secondary battery that includes the gel electrolyte layer 36 may bemanufactured, for example, by the following three types of procedures.

In the first procedure, the cathode 33 and the anode 34 are fabricatedby a fabrication procedure similar to that of the cathode 21 and theanode 22. Specifically, the cathode 33 is fabricated by forming thecathode active material layer 33B on one or both surfaces of the cathodecurrent collector 33A, and the anode 34 is fabricated by forming theanode active material layer 34B on one or both surfaces of the anodecurrent collector 34A. Subsequently, a precursor solution that includesan electrolytic solution, a polymer compound, and a solvent such as anorganic solvent is prepared. Thereafter, the cathode 33 and the anode 34are coated with the precursor solution to form the gel electrolyte layer36. Subsequently, the cathode lead 31 is attached to the cathode currentcollector 33A for example, by a welding method and/or the like, and theanode lead 32 is similarly attached to the anode current collector 34A,for example, by a welding method and/or the like. Subsequently, thecathode 33 and the anode 34 are laminated with the separator 35 inbetween and are spirally wound to fabricate the spirally wound electrodebody 30. Thereafter, the protective tape 37 is adhered to the outermostperiphery thereof. Subsequently, after the spirally wound electrode body30 is sandwiched between two pieces of film-like outer package members40, the outer edges of the outer package members 40 are bonded, forexample, by a thermal fusion bonding method and/or the like to enclosethe spirally wound electrode body 30 in the outer package member 40. Inthis case, the adhesive films 41 are inserted between the cathode lead31 and the outer package member 40 and between the anode lead 32 and theouter package member 40.

In the second procedure, the cathode lead 31 is attached to the cathode33, and the anode lead 32 is attached to the anode 34. Subsequently, thecathode 33 and the anode 34 are laminated with the separator 35 inbetween and are spirally wound to fabricate a spirally wound body thatis a precursor of the spirally wound electrode body 30. Thereafter, theprotective tape 37 is adhered to the outermost periphery thereof.Subsequently, after the spirally wound body is sandwiched between twopieces of the film-like outer package member 40, the outermostperipheries except for one side are bonded, for example, by a thermalfusion bonding method and/or the like. The spirally wound body iscontained in the pouch-like outer package member 40. Subsequently, acomposition for electrolyte is prepared that includes an electrolyticsolution, a monomer as a raw material of the polymer compound, apolymerization initiator, and other materials such as a polymerizationinhibitor where appropriate. The composition for electrolyte is injectedinto the pouch-like outer package member 40. Thereafter, the outerpackage member 40 is hermetically sealed, for example, by a thermalfusion bonding method and/or the like. Subsequently, the monomer isthermally polymerized to form a polymer compound. Thus, the polymercompound is impregnated with the electrolytic solution and the polymercompound is gelated thereby. Accordingly, the gel electrolyte layer 36is formed.

In the third procedure, the spirally wound body is fabricated andcontained in the pouch-like outer package member 40 in a manner similarto that of the foregoing second procedure, except that the separator 35having both surfaces coated with a polymer compound is used. Examples ofthe polymer compound with which the separator 35 is coated include apolymer (a homopolymer, a copolymer, or a multicomponent copolymer) thatincludes vinylidene fluoride as a component. Specific examples of thehomopolymer include polyvinylidene fluoride. Specific examples of thecopolymer include a binary copolymer that includes vinylidene fluorideand hexafluoro propylene as components. Specific examples of themulticomponent copolymer include a ternary copolymer that includesvinylidene fluoride, hexafluoro propylene, and chlorotrifluoroethyleneas components. It is to be noted that other one or more polymercompounds may be used in addition to the polymer that includesvinylidene fluoride as a component. Subsequently, an electrolyticsolution is prepared and is injected into the outer package member 40.Thereafter, the opening of the outer package member 40 is hermeticallysealed, for example, by a thermal fusion bonding method and/or the like.Subsequently, the resultant is heated while a weight is applied to theouter package member 40, and the separator 35 is closely adhered to thecathode 33 and the anode 34 with the polymer compound in between. Thus,the polymer compound is impregnated with the electrolytic solution, andaccordingly, the polymer compound is gelated to form the electrolytelayer 36.

In the third procedure, swollenness of the secondary battery issuppressed more than in the first procedure. Further, in the thirdprocedure, little of the materials such as the monomer as the rawmaterial of the polymer compound and the solvent is left in theelectrolyte layer 36, compared to in the second procedure. Therefore,the formation step of the polymer compound is favorably controlled.Therefore, sufficient adhesive characteristics are obtained between theelectrolyte layer 36 and the cathode 33, the anode 34, and the separator35.

[Functions and Effects of Secondary Battery]

According to the present laminated film type secondary battery, theelectrolytic solution in the electrolyte layer 36 includes theabove-described cyano compound. Therefore, superior batterycharacteristics are obtained for a reason similar to that in thecylindrical type secondary battery. Functions and effects other thanthis are similar to those of the cylindrical type secondary battery.

[1-3. Lithium Metal Secondary Battery (Cylindrical Type and LaminatedFilm Type)]

A secondary battery described herein is a lithium secondary battery(lithium metal secondary battery) in which the capacity of the anode 22is expressed by precipitation and dissolution of lithium metal. Thepresent secondary battery has a configuration similar to that of theabove-described lithium ion secondary battery (cylindrical type) and ismanufactured by procedures similar to those of the above-describedlithium ion secondary battery (cylindrical type) except that the anodeactive material layer 22B is formed of lithium metal.

In this secondary battery, lithium metal is used as the anode activematerial. Therefore, high energy density is obtainable. The anode activematerial layer 22B may exist from the time of assembling. However, theanode active material layer 22B may not exist at the time of assemblingand may be formed by lithium metal precipitated at the time of charge.Further, the anode active material layer 22B may be utilized as acurrent collector and the anode current collector 22A may not beprovided.

The present secondary battery may operate, for example, as follows.Lithium ion is extracted from the cathode 21 and is precipitated aslithium metal on the surface of the anode current collector 22A throughthe electrolytic solution, at the time of charge. On the other hand,lithium metal is dissolved in the electrolytic solution as lithium ionsfrom the anode active material layer 22B, and the lithium ions areinserted to the cathode 21 through the electrolytic solution, at thetime of discharge.

According to the present lithium metal secondary battery, theelectrolytic solution includes the above-described cyano compound.Therefore, superior battery characteristics are obtained for a reasonsimilar to that of the lithium ion secondary battery. Functions andeffects other than this are similar to those of the cylindrical typesecondary battery. It is to be noted that the above-described lithiummetal secondary battery is not limited to the cylindrical type and maybe of a laminated film type. Also in this case, similar effects areobtained.

2. Second Embodiment/Secondary Battery Cyano Compound: The Number ofCyano Group is not Limited+Metal-Based Material

Next, description will be given of a secondary battery of a secondembodiment of the present application.

[2-1. Lithium Ion Secondary Battery (Cylindrical Type)]

The secondary battery of the present embodiment has a configurationsimilar to that of the secondary battery of the first embodiment exceptthat the configuration of the anode 22 and the composition of theelectrolytic solution are different from those in the first embodiment.Therefore, the secondary battery described herein is a lithium ionsecondary battery of a cylindrical type. The elements of the secondarybattery of the first embodiment that have already been described will beused as necessary in the following description.

The anode active material layer 22B of the anode 22 includes ametal-based material as the anode active material. The details of themetal-based material are similar to those described in the firstembodiment. In particular, the metal-based material preferably includesSi, Sn, or both as constituent elements since high energy density isobtained thereby.

It is to be noted that the anode active material layer 22B mayadditionally include one or more of other anode materials that iscapable of inserting and extracting lithium ions when the anode activematerial layer 22B includes the above-described anode material(metal-based material) as the anode active material. Other anodematerial may be, for example, a carbon material, a metal oxide, apolymer compound, or the like and the details thereof are similar tothose described in the first embodiment.

The electrolytic solution includes a cyano compound and the cyanocompound includes a compound represented by the following Formula (19),a compound represented by the following Formula (20), or both. It is tobe noted that the electrolytic solution may include other materials suchas a solvent (excluding the above-described cyano compounds) and anelectrolyte salt. The details of the solvent and the electrolyte saltare similar to those described in the first embodiment.

(R5 and R6 are each one of a hydrocarbon group, an oxygen-containinghydrocarbon group, a cyano-group-containing group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another, and R5, R6, or both include thecyano-group-containing group. A cyano group in thecyano-group-containing group in R5, R6, or both is bonded to an oxygenatom at a terminal of a —O—C(═O)—O— bond with one or more carbon atomsin between.)

(R7 is one of a hydrocarbon group, an oxygen-containing hydrocarbongroup, a cyano-group-containing group, halogenated groups of theforegoing groups, and groups each obtained by bonding two or more of theforegoing groups to one another. R8 is one of a cyano-group-containinggroup, halogenated groups of the foregoing group, and groups eachobtained by bonding two or more of the foregoing groups to one another.A cyano group in the cyano-group-containing group in R8 is bonded to anoxygen atom at a terminal of a —C(═O)—O— bond with one or more carbonatoms in between.)

The cyano compound described herein is one of compounds defined byFormula (19) and by Formula (20), which is different from the compoundin the first embodiment that is one of compounds defined by Formula (1)and by Formula (2). The compound represented by Formula (19) is acompound (carbonate-ester type cyano compound) that includes thecarbonate-ester type bond (—O—C(═O)—O—) as a skeleton. Further, thecompound represented by Formula (20) is a compound (ester type cyanocompound) that includes the ester type bond (—C(═O)—O—) as a skeleton.

One reason why the electrolytic solution includes the cyano compound isthat chemical stability of the electrolytic solution is remarkablyimproved even when the anode 22 includes a metal-based material as theanode active material. Accordingly, a decomposition reaction of theelectrolytic solution is remarkably suppressed, and therefore decreasein discharge capacity is suppressed even when the secondary battery isrepeatedly charged and discharged and is stored.

In detail, when the anode active material is a non-metal-based material(such as a carbon material) having low reactivity, the decompositionreaction of the electrolytic solution resulting from reactivity of thecarbon material is less likely to occur upon charge and discharge.Therefore, discharge capacity is less likely to be influenced dependingon whether or not the cyano compound is present in the electrolyticsolution.

On the other hand, when the anode active material is the metal-basedmaterial having high reactivity, high energy density is obtained but thedecomposition reaction of the electrolytic solution resulting fromreactivity of the metal-based material is remarkable upon charge anddischarge. Therefore, discharge capacity is largely varied depending onwhether or not the cyano compound is present in the electrolyticsolution. Specifically, when the metal-based material is used, thedecomposition reaction of the electrolytic solution resulting fromreactivity of the anode active material easily proceeds if theelectrolytic solution does not include the cyano compound. Therefore,discharge capacity is decreased easily. This tendency is remarkableespecially under severe conditions such as high temperature environment.However, when the electrolytic solution includes the cyano compound, arigid film resulting from the cyano compound is formed on the surface ofthe anode 22 upon charge and discharge, and therefore the anode 22 isprotected from the electrolytic solution. Accordingly, the decompositionreaction of the electrolytic solution resulting from reactivity of theanode active material is less likely to proceed, and therefore dischargecapacity is maintained easily. This tendency is remarkable especiallywhen the secondary battery is charged, discharged, and stored undersevere temperature environment such as high temperature environment.

In Formula (19), the types of R5 and R6 is not particularly limited aslong as R5 and R6 are each one of a hydrocarbon group, anoxygen-containing hydrocarbon group, a cyano-group-containing group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another, as describedabove.

It is to be noted that it is made a condition that R5, R6, or bothinclude the cyano-group-containing group (that is, a cyano group). Theabove-described advantages are obtained independently of the types of R5and R6 when R5, R6, or both include a cyano group.

Moreover, it is made a condition that a cyano group in thecyano-group-containing group is bonded to an oxygen atom at a terminalof the —O—C(═O)—O— bond with one or more carbon atoms in between. Inother words, it is necessary that the cyano group is not directly bondedto the oxygen atom and is indirectly bonded to the oxygen atom with acarbon atom in between. One reason for this is that the above-describedadvantages are obtained independently of the types of R5 and R6 sincethe cyano group is indirectly bonded to the oxygen atom.

It is to be noted that R5 and R6 may be the same type of group or may bedifferent types of group. Further, R5 and R6 may be bonded to each otherand the bonded R5 and R6 may form a ring.

In Formula (20), the type of R7 is not particularly limited as long asR7 is one of a hydrocarbon group, an oxygen-containing hydrocarbongroup, a cyano-group-containing group, halogenated groups of theforegoing groups, and groups each obtained by bonding two or more of theforegoing groups to one another, as described above. Further, the typeof R8 is not particularly limited as long as R8 is one of acyano-group-containing group, halogenated groups, and groups eachobtained by bonding two or more of the foregoing groups to one another,as described above.

It is to be noted that it is made a condition that a cyano group in thecyano-group-containing group is bonded to an oxygen atom at a terminalof the —C(═O)—O— bond with one or more carbon atoms in between. Onereason for this is that the above-described advantages are obtainedindependently of the type of R7 since the cyano group is indirectlybonded to an oxygen atom.

It is to be noted that R7 and R8 may be bonded to each other and thebonded R7 and R8 may form a ring.

Here, the details of R5 to R8, that is, what is referred to by each ofthe terms “hydrocarbon group”, “oxygen-containing hydrocarbon group”,“cyano-group-containing group”, “halogenated group”, “groups eachobtained by bonding two or more of the foregoing groups to one another”is similar to that described for R1 to R4 in the first embodiment. Outof the foregoing groups, it goes without saying that the hydrocarbongroup includes a saturated hydrocarbon group and an unsaturatedhydrocarbon group, and the oxygen-containing hydrocarbon groupcorresponds to an oxygen-containing saturated hydrocarbon group.

Specific examples of the cyano compound may be as follows. Examples ofthe carbonate-ester type cyano compound may include compoundsrepresented by the following Formula (19-1) to Formula (19-31). Further,examples of the ester type cyano compound may include compoundsrepresented by the following Formula (20-1) to Formula (20-28). It is tobe noted that the cyano compound may be other compounds that satisfy thecondition shown in Formula (19) or in Formula (20).

A content of the cyano compound in the electrolytic solution is notparticularly limited. However, in particular, the content of the cyanocompound is preferably from 0.01 wt % to 20 wt % both inclusive, andmore preferably from 0.5 wt % to 20 wt % both inclusive, since a highereffect is obtained thereby.

The details of operation and of a manufacturing method of the presentsecondary battery may be similar to those in the first embodiment(cylindrical type) except that the composition of the electrolyticsolution is different from that in the first embodiment, for example.

According to the present secondary battery of a cylindrical type, theanode active material layer 22B of the anode 22 includes the metal-basedmaterial and the electrolytic solution includes the cyano compound. Inthis case, as described above, chemical stability of the electrolyticsolution is specifically improved, and therefore the decompositionreaction of the electrolytic solution is remarkably suppressed even whenthe electrolytic solution includes the metal-based material having highreactivity as the anode active material. Accordingly, the electrolyticsolution is less likely to be decomposed even when the secondary batteryis charged and discharged or is stored. Therefore, superior batterycharacteristics are obtained.

In particular, when the metal-based material is one of a simplesubstance, an alloy, and a compound of Si and a simple substance, analloy, and a compound of Sn, a higher effect is obtained. Further, whenthe content of the cyano compound in the electrolytic solution is from0.01 wt % to 20 wt % both inclusive, a higher effect is obtained.

[2-2. Lithium Ion Secondary Battery (Laminated Film Type)]

It is to be noted that the secondary battery of the present embodimentmay be of a laminated film type instead of the above-describedcylindrical type. A configuration of the secondary battery of thelaminated film type is similar to that in the first embodiment exceptthat the composition of the electrolytic solution is different from thatin the first embodiment. Also in this case, superior batterycharacteristics are obtained.

3. Third Embodiment/Electrolytic Solution and Secondary Battery CyanoCompound: The Number of Cyano Compound is not Limited+Non-Cyano Compound

Next, description will be given of an electrolytic solution and asecondary battery of a third embodiment of the present application.

[3-1. Lithium Ion Secondary Battery (Cylindrical Type)]

The secondary battery of the present embodiment has a configurationsimilar to that of the secondary battery of the first embodiment exceptthat the composition of the electrolytic solution is different from thatin the first embodiment. Therefore, the secondary battery describedherein is a lithium ion secondary battery of a cylindrical type. Theelements of the secondary battery of the first embodiment that havealready been described will be used as necessary in the followingdescription.

The electrolytic solution includes one or more of cyano compounds andone or more of non-cyano compounds. The details of the cyano compoundsare similar to those of the cyano compounds described in the secondembodiment, and the details of the non-cyano compounds are similar tothose of the non-cyano compounds described in the first embodiment.Therefore, description thereof will be omitted. It is to be noted thatthe electrolytic solution may include other materials such as a solventand an electrolytic salt.

One reason why the electrolytic solution includes the cyano compound andthe non-cyano compound is that chemical stability is improved due to asynergetic function thereof compared to in a case where only one of thecyano compound and the non-cyano compound is included, and therefore thedecomposition reaction is suppressed. In detail, a rigid film resultingfrom the cyano compound and the non-cyano compound is mainly formed onthe surface of the anode 22 upon charge and discharge, and therefore thedecomposition reaction of the electrolytic solution due to presence ofthe anode 22 having high reactivity is suppressed. Accordingly, decreasein discharge capacity is suppressed even when the secondary battery isrepeatedly charged and discharged or is stored. This tendency isremarkable especially when the secondary battery is charged anddischarged or is stored under severe temperature environment such ashigh temperature environment.

The content of the cyano compound in the electrolytic solution is notparticularly limited. However, in particular, the content of the cyanocompound is preferably from 0.01 wt % to 20 wt % both inclusive, andmore preferably from 0.5 wt % to 20 wt % both inclusive, since a highereffect is obtained thereby.

The content of the non-cyano compound in the electrolytic solution isnot particularly limited. However, the content of the non-cyano compoundis preferably from 0.001 wt % to 2 wt % both inclusive, since a highereffect is obtained thereby.

The details of operation and of a manufacturing method of the presentsecondary battery may be similar to those in the first embodiment(cylindrical type) except that the composition of the electrolyticsolution is different from that in the first embodiment.

According to the present secondary battery of a cylindrical type, theelectrolytic solution includes the cyano compound and the non-cyanocompound. In this case, as described above, the decomposition reactionof the electrolytic solution is suppressed due to the synergeticfunction of the cyano compound and the non-cyano compound even undersevere temperature environment such as high temperature environment.Accordingly, the electrolytic solution is less likely to be decomposedeven when the secondary battery is charged and discharged or is storedunder severe temperature environment. Therefore superior batterycharacteristics are obtained.

In particular, when the content of the cyano compound in theelectrolytic solution is from 0.01 wt % to 20 wt % both inclusive, orwhen the content of the non-cyano compound in the electrolytic solutionis from 0.001 wt % to 2 wt % both inclusive, a higher effect isobtained.

[3-2. Lithium Ion Secondary Battery (Laminated Film Type)]

It is to be noted that the secondary battery of the present embodimentmay be of a laminated film type instead of the above-describedcylindrical type. A configuration of the secondary battery of thelaminated film type is similar to that in the first embodiment exceptthat the composition of the electrolytic solution is different from thatin the first embodiment. Also in this case, superior batterycharacteristics are obtained.

[3-3. Lithium Metal Secondary Battery (Cylindrical Type and LaminatedFilm Type)]

Moreover, the secondary battery of the present embodiment may be alithium metal secondary battery instead of the above-described lithiumion secondary battery. A battery structure in this case may be either ofa cylindrical type or a laminated film type. A configuration of thelithium metal secondary battery is similar to that in the firstembodiment except that the configuration of the anode and thecomposition of the electrolytic solution are different from those in thefirst embodiment. Also in this case, superior battery characteristicsare obtained.

4. Applications of Secondary Battery

Next, description will be given of application examples of theabove-described secondary batteries.

Applications of the secondary battery are not particularly limited aslong as the secondary battery is used for applications such as amachine, a device, an instrument, an apparatus, a system (collectiveentity of a plurality of devices and the like) that are capable of usingthe secondary battery, for example, as a driving electric power source,an electric power storage source for electric power storage, or thelike. It is to be noted that the secondary battery used as an electricpower source may be a main electric power source (electric power sourceused preferentially), or may be an auxiliary electric power source(electric power source used instead of a main electric power source orused being switched from the main electric power source). When thesecondary battery is used as an auxiliary electric power source, thetype of the main electric power source is not limited to a secondarybattery.

Examples of applications of the secondary battery include electronicapparatuses (including mobile electronic apparatuses) such as videocamcorders, digital still cameras, mobile phones, notebook personalcomputers, cordless phones, headphone stereos, portable radios, portabletelevisions, and personal digital assistants. Further examples thereofinclude mobile lifestyle electric appliances such as electric shavers;memory devices such as backup electric power sources and memory cards;electric power tools such as electric drills and electric saws; batterypacks used as an attachable and detachable electric power source, forexample, for notebook personal computers or the like; medical electronicapparatuses such as pacemakers and hearing aids; electric vehicles suchas electric automobiles (including hybrid automobiles); and electricpower storage systems such as home battery systems for storing electricpower, for example, for emergency or the like. It goes without sayingthat the secondary battery may be also used for applications other thanthe foregoing applications.

In particular, the secondary battery is effective in applications suchas the battery pack, the electric vehicle, the electric power storagesystem, the electric power tool, and the electronic apparatus. In theseapplications, since superior battery characteristics are demanded, theperformance thereof is effectively improved by using the secondarybattery according to the embodiments of the present application. It isto be noted that the battery pack is an electric power source that usesa secondary battery, such as a so-called assembled battery. The electricvehicle is a vehicle that operates (runs) with the use of a secondarybattery as a driving electric power source. As described above, theelectric vehicle may be an automobile (such as a hybrid automobile) thatalso includes a drive source other than a secondary battery. Theelectric power storage system is a system that uses a secondary batteryas an electric power storage source. For example, in a home electricpower storage system, electric power is stored in the secondary batterythat is an electric power storage source, and the electric power isconsumed as necessary. Therefore, for example, home electric productsand the like become usable. The electric power tool is a tool in which amovable section (such as a drill) is moved with the use of a secondarybattery as a driving electric power source. The electronic apparatus isan apparatus that executes various functions with the use of a secondarybattery as a driving electric power source (electric power supplysource).

Here, description will be specifically given of some applicationexamples of the secondary battery. It is to be noted that configurationsof the respective application examples explained below are merelyexamples, and may be changed as appropriate.

[4-1. Battery Pack]

FIG. 5 illustrates a block configuration of a battery pack. The batterypack may include, for example, a control section 61, an electric powersource 62, a switch section 63, a current measurement section 64, atemperature detection section 65, a voltage detection section 66, aswitch control section 67, a memory 68, a temperature detection device69, a current detection resistance 70, a cathode terminal 71, and ananode terminal 72 in a housing 60 that is formed of materials such as aplastic material.

The control section 61 controls operation of the battery pack as a whole(including a used state of the electric power source 62), and mayinclude, for example, a central processing unit (CPU) and/or the like.The electric power source 62 includes one or more secondary batteries(not illustrated). The electric power source 62 may be, for example, anassembled battery that includes two or more secondary batteries. Thesecondary batteries may be connected to one another in series, inparallel, or in a combination thereof. To give an example, the electricpower source 62 includes six secondary batteries connected two inparallel and three in series.

The switch section 63 switches the used state of the electric powersource 62 (whether or not the electric power source 62 is connectable toan external device) according to an instruction of the control section61. The switch section 63 may include, for example, a charge controlswitch, a discharge control switch, a charging diode, a dischargingdiode, and the like (not illustrated). The charge control switch and thedischarge control switch each may be, for example, a semiconductorswitch such as a field-effect transistor (MOSFET) that uses a metaloxide semiconductor.

The current measurement section 64 measures a current with the use ofthe current detection resistance 70, and outputs the measurement resultto the control section 61. The temperature detection section 65 measurestemperature with the use of the temperature detection device 69, andoutputs the measurement result to the control section 61. Thetemperature measurement result may be used, for example, in a case inwhich the control section 61 controls charge and discharge at the timeof abnormal heat generation, or in a case in which the control section61 performs correction processing at the time of calculating remainingcapacity. The voltage detection section 66 measures a voltage of thesecondary battery in the electric power source 62, performsanalog-to-digital conversion (A/D conversion) on the measured voltage,and supplies the resultant to the control section 61.

The switch control section 67 controls operation of the switch section63 according to signals inputted from the current measurement section 64and the voltage measurement section 66.

The switch control section 67 disconnects the switch section 63 (chargecontrol switch) so that a charge current is prevented from flowing in acurrent path of the electric power source 62 when a battery voltagereaches an overcharge detection voltage, for example. Thus, the electricpower source 62 is allowed only to be discharged through the dischargingdiode. It is to be noted that the switch control section 67 blocks thecharge current in the case where a large current flows at the time ofcharge, for example.

Moreover, the switch control section 67 disconnects the switch section63 (discharge control switch) so that a discharge current is preventedfrom flowing in the current path of the electric power source 62 when abattery voltage reaches an over-discharge detection voltage, forexample. Thus, the electric power source 62 is allowed only to becharged through the charging diode. It is to be noted that the switchcontrol section 67 blocks the discharge current in the case where alarge current flows at the time of discharge, for example.

It is to be noted that, in the secondary battery, for example, theovercharge detection voltage may be 4.20 V±0.05 V, and theover-discharge detection voltage may be 2.4 V±0.1 V.

The memory 68 may be, for example, a memory such as an EEPROM that is anonvolatile memory. The memory 68 may store, for example, numericalvalues calculated by the control section 61 and information (such as aninternal resistance in the initial state) of the secondary batterymeasured in a manufacturing step. It is to be noted that, when thememory 68 stores a full charge capacity of the secondary battery, thecontrol section 61 comprehends information such as remaining capacity.

The temperature detection device 69 measures temperature of the electricpower source 62, and outputs the measurement result to the controlsection 61. The temperature detection device 69 may be a device such asa thermistor.

The cathode terminal 71 and the anode terminal 72 are terminalsconnected to an external device (such as a notebook personal computer)driven with the use of the battery pack, or terminals connected to anexternal device (such as a battery charger) provided for charging thebattery pack. The electric power source 62 is charged and dischargedthrough the cathode terminal 71 and the anode terminal 72.

[4-2. Electric Vehicle]

FIG. 6 illustrates a block configuration of a hybrid automobile that isan example of an electric vehicle. This electric vehicle may include,for example, a control section 74, an engine 75, an electric powersource 76, a driving motor 77, a differential 78, an electric generator79, a transmission 80, a clutch 81, inverters 82 and 83, and varioussensors 84 in a housing 73 made of metal. In addition thereto, theelectric vehicle may include, for example, a front tire drive shaft 85and a front tire 86 that are connected to the differential 78 and thetransmission 80, a rear tire drive shaft 87, and a rear tire 88.

The electric vehicle runs with the use of one of the engine 75 and themotor 77 as a drive source. The engine 75 is a main power source, andmay be an engine such as a petrol engine. In the case where the engine75 is used as a power source, drive power (torque) of the engine 75 maybe transferred, for example, to the front tire 86 or to the rear tire 88through the differential 78, the transmission 80, and the clutch 81 thatare drive sections. It is to be noted that the torque of the engine 75is also transferred to the electric generator 79. Using the torque, theelectric generator 79 generates alternating-current electric power, andthe alternating-current electric power is converted to direct-currentelectric power through the inverter 83, and the thus-converteddirect-current electric power is stored in the electric power source 76.On the other hand, in the case where the motor 77 that is a conversionsection is used as a power source, electric power (direct-currentelectric power) supplied from the electric power source 76 is convertedto alternating-current electric power through the inverter 82. The motor77 is driven by the alternating-current electric power. Drive power(torque) converted from the electric power by the motor 77 may betransferred, for example, to the front tire 86 or to the rear tire 88through the differential 78, the transmission 80, and the clutch 81 thatare the drive sections.

It is to be noted that a scheme may be adopted in which, when speed ofthe electric vehicle is reduced by an unillustrated brake mechanism, theresistive force at the time of speed reduction is transferred to themotor 77 as torque, and the motor 77 generates alternating-currentelectric power by the torque. It is preferable that thealternating-current electric power be converted to direct-currentelectric power through the inverter 82, and the direct-currentregenerative electric power be stored in the electric power source 76.

The control section 74 controls operation of the electric vehicle as awhole, and, for example, may include a CPU and/or the like. The electricpower source 76 includes one or more secondary batteries (notillustrated). The electric power source 76 may be connected to anexternal electric power source, and be allowed to store electric powerby receiving electric power from the external electric power source. Thevarious sensors 84 may be used, for example, for controlling the numberof rotations of the engine 75 or for controlling opening level (throttleopening level) of an unillustrated throttle valve. The various sensors84 may include sensors such as, a speed sensor, an acceleration sensor,and an engine rotation frequency sensor.

It is to be noted that the description has been given above of a casewhere the electric vehicle is a hybrid automobile. However, the electricvehicle may be a vehicle (electric automobile) that operates by usingonly the electric power source 76 and the motor 77 without using theengine 75.

[4-3. Electric Power Storage System]

FIG. 7 illustrates a block configuration of an electric power storagesystem. The electric power storage system may include, for example, acontrol section 90, an electric power source 91, a smart meter 92, and apower hub 93, inside a house 89 such as a general residence and acommercial building.

In this example, the electric power source 91 may be connected to anelectric device 94 arranged inside the house 89, and may be connectableto an electric vehicle 96 parked outside the house 89, for example.Further, the electric power source 91 may be connected to a privatepower generator 95 provided in the house 89 through the power hub 93,and may be connectable to an external concentrating electric powersystem 97 thorough the smart meter 92 and the power hub 93, for example.

It is to be noted that the electric device 94 may encompass, forexample, one or more home electric appliances such as a refrigerator, anair conditioner, a television, and a water heater. The private powergenerator 95 may be, for example, one or more of generators such as asolar power generator and a wind-power generator. The electric vehicle96 may be, for example, one or more of vehicles such as an electricautomobile, an electric motorcycle, and a hybrid automobile. Theconcentrating electric power system 97 may be, for example, one or moreof electric power systems such as a thermal power plant, a nuclear powerplant, a hydraulic power plant, and a wind power plant.

The control section 90 controls operation of the electric power storagesystem as a whole (including a used state of the electric power source91), and, may include, for example, a CPU and/or the like. The electricpower source 91 includes one or more secondary batteries (notillustrated). The smart meter 92 may be, for example, an electric powermeter compatible with a network provided in the house 89 which is aconsumer of electric power, and may be communicable with a supplier ofelectric power. Accordingly, for example, while the smart meter 92communicates with the outside as necessary, the smart meter 92 controlsthe balance between supply and demand in the house 89 and thereby allowseffective and stable energy supply.

In the electric power storage system, for example, electric power isstored in the electric power source 91 from the concentrating electricpower system 97 that is an external electric power source through thesmart meter 92 and the power hub 93, and electric power is stored in theelectric power source 91 from the private power generator 95 that is anindependent electric power source through the power hub 93. The electricpower stored in the electric power source 91 is supplied to the electricdevice 94 or to the electric vehicle 96 as necessary according to aninstruction of the control section 90. Therefore, the electric device 94becomes operable, and the electric vehicle 96 becomes chargeable. Inother words, the electric power storage system is a system that achievesstoring and supplying of electric power in the house 89 with the use ofthe electric power source 91.

The electric power stored in the electric power source 91 is used on anoptional basis. Therefore, for example, electric power may be stored inthe electric power source 91 from the concentrating electric powersystem 97 in the middle of the night when an electric rate isinexpensive, and the electric power stored in the electric power source91 may be used during daytime hours when the electric rate is expensive.

It is to be noted that the above-described electric power storage systemmay be provided for each household (family unit), or may be provided fora plurality of households (a plurality of family units).

[4-4. Electric Power Tool]

FIG. 8 illustrates a block configuration of an electric power tool. Theelectric power tool may be, for example, an electric drill, and mayinclude, for example, a control section 99 and an electric power source100 in a tool body 98 made of materials such as a plastic material. Forexample, a drill section 101 that is a movable section may be attachedto the tool body 98 in an operable (rotatable) manner.

The control section 99 controls operation of the electric power tool asa whole (including a used state of the electric power source 100), andmay include, for example, a CPU and/or the like. The electric powersource 100 includes one or more secondary batteries (not illustrated).The control section 99 allows electric power to be supplied from theelectric power source 100 to the drill section 101 as necessary tooperate the drill section 101 according to manipulation of anunillustrated operation switch.

EXAMPLES

Specific Examples of the embodiments of the present application will bedescribed in detail.

(1) Examples of First Embodiment

First, various characteristics of the secondary battery of the firstembodiment were examined.

Examples 1-1 to 1-26

The lithium ion secondary battery of a cylindrical type shown in FIGS. 1and 2 was fabricated by the following procedures.

Upon fabricating the cathode 21, first, lithium carbonate (Li₂CO₃) andcobalt carbonate (CoCO₃) were mixed at a mole ratio ofLi₂CO₃:CoCO₃=0.5:1. Subsequently, the mixture was burned (at 900° C. for5 hours) in the air and a lithium-cobalt composite oxide (LiCoO₂) wasobtained thereby. Subsequently, 91 parts by mass of the cathode activematerial (LiCoO₂), 3 parts by mass of the cathode binder (polyvinylidenefluoride: PVDF), and 6 parts by mass of the cathode conductive agent(graphite) were mixed to prepare a cathode mixture. Subsequently, thecathode mixture was dispersed into an organic solvent(N-methyl-2-pyrrolidone: NMP) to prepare paste cathode mixture slurry.Subsequently, the cathode mixture slurry was coated uniformly on bothsurfaces of the strip-like cathode current collector 21A (an aluminumfoil having a thickness of 20 μm) with the use of a coating device, andwas dried to form the cathode active material layer 21B. Lastly, thecathode active material layer 21B was compression-molded with the use ofa roll-pressing machine.

Upon fabricating the anode 22, first, 90 parts by mass of the anodeactive material (artificial graphite) and 10 parts by mass of the anodebinder (PVDF) were mixed to obtain an anode mixture. Subsequently, theanode mixture was dispersed into an organic solvent (NMP) to obtainpaste anode mixture slurry. Subsequently, the anode mixture slurry wascoated uniformly on both surfaces of the stripe-like anode currentcollector 22A (a electrolyte copper foil having a thickness of 15 μm)with the use of a coating device, and was dried to form the anode activematerial layer 22B. Lastly, the anode active material layer 22B wascompression-molded with the use of a roll-pressing machine.

Upon preparing the electrolytic solution, the electrolyte salt (LiPF₆)was dissolved in the solvent (ethylene carbonate (EC) and dimethylcarbonate (DMC)), and the cyano compound was added thereto whereappropriate as shown in Table 1. In this example, the composition of thesolvent was set to be EC:DMC=50:50 at weight ratio and the content ofthe electrolyte salt with respect to the solvent was set to be 1 mol/kg.It is to be noted that, in the sake of comparison, other cyano compoundrepresented by Formula (18-1) or Formula (18-2) was also used.

Upon assembling the secondary battery, first, the cathode lead 25 madeof aluminum was welded to the cathode current collector 21A and theanode lead 26 made of nickel was welded to the anode current collector22A. Subsequently, the cathode 21 and the anode 22 were laminated withthe separator 23 (microporous polypropylene film having a thickness of25 μm) in between and were spirally wound. Thereafter, the end of thewound portion was fixed with an adhesive tape to fabricate the spirallywound electrode body 20. Subsequently, the center pin 24 was inserted inthe center hollow of the spirally wound electrode body 20. Subsequently,the spirally wound electrode body 20 was sandwiched between the pair ofinsulating plates 12 and 13 and contained inside the battery can 11 thatwas made of iron and plated with nickel. In this example, one end of thecathode lead 25 was welded to the safety valve mechanism 15, and one endof the anode lead 26 was welded to the battery can 11. Subsequently, theelectrolytic solution was injected into the battery can 11 bydepressurization to allow the separator 23 to be impregnated with theelectrolytic solution. Lastly, the battery cover 14, the safety valvemechanism 15, and the PTC device 16 were swaged with the gasket 17 inbetween to be fixed onto the open end of the battery can 11. Thus, thesecondary battery of a cylindrical type was completed. It is to be notedthat, upon fabricating the secondary battery, the thickness of thecathode active material layer 21B was adjusted so that lithium metal didnot precipitate on the anode 22 when the battery was fully charged.

Battery characteristics (cycle characteristics and conservationcharacteristics) of the secondary battery were examined and resultsshown in Table 1 were obtained.

Upon examining cycle characteristics, the secondary battery was chargedand discharged for 1 cycle in an ambient temperature environment (23°C.) to stabilize the battery state. Thereafter, the secondary batterywas charged and discharged for another cycle in the same environment,and the discharge capacity thereof was measured. Subsequently, thesecondary battery was charged and discharged repeatedly in the sameenvironment until the total number of cycle reached 300, and then, thedischarge capacity thereof was measured. Based on this result, cycleretention ratio (%)=(discharge capacity at the 300th cycle/dischargecapacity at the 2nd cycle)×100 was calculated. At the time of charging,the secondary battery was charged at a current of 0.2 C until thevoltage reached the upper limit voltage of 4.2 V, and then, thesecondary battery was charged at a voltage of 4.2 V until the currentreached 0.05 C. At the time of discharging, the secondary battery wasdischarged at a current of 0.2 C until the voltage reached the finalvoltage of 2.5 V. “0.2 C” and “0.05 C” refer to current values withwhich the battery capacity (theoretical capacity) is completelydischarged in 5 hours and in 20 hours, respectively.

Upon examining conservation characteristics, the secondary batteryhaving a battery state that was stabilized by procedures similar tothose in examining the cycle characteristics was used. The secondarybattery was charged and discharged for 1 cycle in the ambienttemperature environment (23° C.), and the discharge capacity thereof wasmeasured. Subsequently, the secondary battery was stored in a constanttemperature bath (80° C.) for 10 days in a state that the secondarybattery was charged again. Thereafter, the secondary battery wasdischarged in an ambient temperature environment (23° C.), and dischargecapacity thereof was measured. Based on this result, conservationretention ratio (%)=(discharge capacity after storing/discharge capacitybefore storing)×100 was calculated. Conditions of charge and dischargewere similar to those upon examining cycle characteristics.

TABLE 1 Anode active material: artificial graphite Cycle ConservationCyano compound retention retention Electrolyte Content ratio ratioExample salt Solvent Type (wt %) (%) (%) 1-1 LiPF₆ EC + DMC Formula(1-3) 0.01 68 82 1-2 0.1 72 82 1-3 0.5 75 84 1-4 1 80 84 1-5 2 85 84 1-65 85 84 1-7 10 83 82 1-8 20 82 82 1-9 Formula (1-8) 2 85 84 1-10 Formula(1-10) 84 82 1-11 Formula (1-11) 83 83 1-12 Formula (1-12) 84 83 1-13Formula (1-14) 82 83 1-14 Formula (1-15) 84 83 1-15 Formula (2-8) 2 7883 1-16 Formula (2-13) 0.01 66 82 1-17 0.1 70 82 1-18 0.5 72 83 1-19 178 83 1-20 2 80 83 1-21 5 80 83 1-22 10 80 82 1-23 20 78 82 1-24 LiPF₆EC + DMC — — 65 81 1-25 Formula (18-1) 2 62 75 1-26 Formula (18-2) 2 5560

When a carbon material (artificial graphite) was used as the anodeactive material, battery characteristics were largely varied dependingon whether or not the cyano compound was present in the electrolyticsolution.

In detail, the example (Example 1-24) in which the cyano compound orother cyano compound was not used was used as a reference. In examples(Examples 1-25 and 1-26) in which other cyano compounds were used, bothcycle retention ratio and conservation retention ratio were decreased.On the other hand, in examples (Examples 1-1 to 1-23) in which the cyanocompounds were used, cycle retention ratio was increased whileconservation retention ratio was maintained.

This result shows that, in a case where the carbonate-ester type cyanocompound represented by Formula (1) is used, the decomposition reactionof the electrolytic solution is specifically suppressed when the numberof cyano group in R2 (cyano-group-containing group) is adjustedappropriately according to the type of R1 (group other than acyano-group-containing group).

Specifically, when R1 is a saturated hydrocarbon group (—CH₃) that doesnot include the unsaturated carbon bond and R2 is acyano-group-containing group (—CH₂—CN) that does not include theunsaturated carbon bond, battery characteristics are varied according tothe number of cyano group in R2. In this case, when the number of cyanogroup is one, the decomposition reaction of the electrolytic solution isnot suppressed. Therefore, cycle retention ratio and conservationretention ratio are rather decreased. On the other hand, when the numberof cyano group is two or larger (two, in this example), thedecomposition reaction of the electrolytic solution is specificallysuppressed. Therefore, cycle retention ratio is increased while decreasein conservation retention ratio is suppressed.

Moreover, when only R2 includes the cyano-group-containing group and R1or R2 includes the unsaturated carbon bond, the decomposition reactionof the electrolytic solution is specifically suppressed even when thenumber of cyano group in R2 is one. Therefore, cycle retention ratio isincreased also in this case.

It is to be noted that the tendency described above for thecarbonate-ester type cyano compound was similarly obtained in an examplein which the ester type cyano compound represented by Formula (2) wasused.

In particular, in examples in which the cyano compound was used, highcycle retention ratio and high conservation retention ratio wereobtained when the content of the cyano compound in the electrolyticsolution was from 0.01 wt % to 20 wt % both inclusive.

Examples 2-1 to 2-23

As shown in Table 2, secondary batteries were fabricated by proceduressimilar to those in Examples 1-1 to 1-24 except that the non-cyanocompound was added to the electrolytic solution, and variouscharacteristics thereof were examined.

TABLE 2 Anode active material: artificial graphite Cyano CycleConservation compound Non-cyano compound retention retention ElectrolyteContent Content ratio ratio Example salt Solvent Type (wt %) Type (wt %)(%) (%) 2-1 LiPF₆ EC + DMC Formula 2 Formula (3- 0.2 85 89 (1-3) 1) 2-2Formula 85 88 (4-1) 2-3 Formula 85 90 (5-1) 2-4 LiPF₂O₂ 0.001 85 88 2-50.1 85 89 2-6 0.2 85 90 2-7 1 85 88 2-8 2 85 88 2-9 Li₂PFO₃ 0.2 85 902-10 Formula 2 Formula 0.2 80 87 (2-13) (3-1) 2-11 Formula 80 86 (4-1)2-12 Formula 80 88 (5-1) 2-13 LiPF₂O₂ 0.001 80 84 2-14 0.1 80 86 2-150.2 80 87 2-16 1 80 86 2-17 2 80 86 2-18 Li₂PFO₃ 0.2 80 86 2-19 LiPF₆EC + DMC — — Formula 0.2 77 82 (3-1) 2-20 Formula 76 82 (4-1) 2-21Formula 78 81 (5-1) 2-22 LiPF₂O₂ 78 82 2-23 Li₂PFO₃ 77 82

Even when the electrolytic solution included the non-cyano compoundtogether with the cyano compound, high cycle retention ratio and highconservation retention ratio were obtained. In particular, in examplesin which the electrolytic solution included the cyano compound,conservation retention ratio was further increased when the electrolyticsolution further included the non-cyano compound. In this case, highconservation retention ratio was obtained when the content of thenon-cyano compound in the electrolytic solution was from 0.001 wt % to 2wt % both inclusive.

Examples 3-1 to 3-24

As shown in Table 3, secondary batteries were fabricated by proceduressimilar to those in Examples 1-1 to 1-24 except that the composition ofthe solvent was changed, and various characteristics thereof wereexamined.

The types of the solvent were as follows. The solvent used incombination with EC was diethyl carbonate (DEC), ethyl methyl carbonate(EMC), or propyl carbonate (PC). The unsaturated cyclic ester carbonatewas vinylene carbonate (VC). The halogenated ester carbonate was4-fluoro-1,3-dioxolan-2-one (FEC), trans-4,5-difluoro-1,3-dioxolan-2-one(t-DFEC), or bis(fluoromethyl) carbonate (DFDMC). The sultone waspropene sultone (PRS). The acid anhydride was succinic anhydride (SCAH)or sulfopropionic anhydride (PSAH).

The composition of the solvent was set to be EC:PC:DMC=10:20:70 atweight ratio. Further, in the solvent, the content of VC was 2 wt %, thecontent of FEC, t-DFEC, or DFDMC was 5 wt %, and the content of PRS,SCAH, or PSAH was 1 wt %.

TABLE 3 Anode active material: artificial graphite Cycle Cyano compoundretention Conservation Content ratio retention ratio Example Electrolytesalt Solvent Type (wt %) (%) (%) 3-1 LiPF₆ EC + DEC Formula (1- 2 82 863-2 EC + EMC 3) 84 86 3-3 EC + PC + DMC 84 86 3-4 EC + VC 87 88 3-5 DMCFEC 90 90 3-6 t-DFEC 87 88 3-7 DFDMC 88 89 3-8 PRS 88 93 3-9 SCAH 88 923-10 PSAH 90 94 3-11 EC + DEC Formula (2- 2 78 84 3-12 EC + EMC 13) 7984 3-13 EC + PC + DMC 78 84 3-14 EC + VC 85 85 3-15 DMC FEC 86 86 3-16t-DFEC 83 85 3-17 DFDMC 83 85 3-18 PRS 84 88 3-19 SCAH 84 87 3-20 PSAH85 89 3-21 LiPF₆ EC + VC — — 80 84 3-22 DMC FEC 79 81 3-23 t-DFEC 79 803-24 DFDMC 78 81

Even when the composition of the solvent was changed, high cycleretention ratio and high conservation ratio were obtained when theelectrolytic solution included the cyano compound. In particular, cycleretention ratio and conservation retention ratio were further increasedwith some composition of the solvent.

Examples 4-1 to 4-6

As shown in Table 4, secondary batteries were fabricated by proceduressimilar to those in Examples 1-1 to 1-23 except that the composition ofthe electrolyte salt was changed, and various characteristics thereofwere examined.

The type of the electrolyte salt was lithium tetrafluoroborate (LiBF₄),bis[oxalato-O,O′] lithium borate (LiBOB) represented by Formula (13-6),or bis(trifluoromethane sulfonyl) imide lithium (LiN(CF₃SO₂)₂: LiTFSI).The content of LiPF₆ with respect to the solvent was set to be 0.9mol/kg, and the content of LiBF₄ or the like with respect to the solventwas set to be 0.1 mol/kg.

TABLE 4 Anode active material: artificial graphite Cycle ConservationCyano compound retention retention Content ratio ratio ExampleElectrolyte salt Solvent Type (wt %) (%) (%) 4-1 LiPF₆ LiBF₄ EC + DMCFormula (1-3) 2 85 90 4-2 LiBOB 85 91 4-3 LiTFSI 85 90 4-4 LiPF₆ LiBF₄EC + DMC Formula (2-13) 2 80 86 4-5 LiBOB 80 86 4-6 LiTFSI 80 85

Even when the composition of the electrolyte salt was changed, highcycle retention ratio and high conservation retention ratio wereobtained when the electrolytic solution included the cyano compound. Inparticular, conservation retention ratio was further increased when theelectrolytic solution included LiBF₄ or the like.

Examples 5-1 to 5-26, 6-1 to 6-23, 7-1 to 7-24, and 8-1 to 8-6

As shown in Tables 5 to 8, secondary batteries were fabricated byprocedures similar to those in Examples 1-1 to 1-26, 2-1 to 2-23, 3-1 to3-24, and 4-1 to 4-6 except that a metal-based material (silicon) wasused as the anode active material, and various characteristics thereofwere examined.

Upon fabricating the anode 22, silicon was deposited on both surfaces ofthe anode current collector 22A by an electron beam evaporation methodto form the anode active material layer 22B. In this example, thedeposition process was repeated for ten times until the thickness of theanode active material layer 22B on one surface of the anode currentcollector 22A became 6 μm.

TABLE 5 Anode active material: silicon Cycle Conservation Cyano compoundretention retention Electrolyte Content ratio ratio Example salt SolventType (wt %) (%) (%) 5-1 LiPF₆ EC + DMC Formula (1-3) 0.01 42 82 5-2 0.145 82 5-3 0.5 50 83 5-4 1 62 85 5-5 2 65 85 5-6 5 65 84 5-7 10 63 83 5-820 60 82 5-9 Formula (1-8) 2 60 86 5-10 Formula (1-10) 60 86 5-11Formula (1-11) 55 84 5-12 Formula (1-12) 62 87 5-13 Formula (1-14) 58 825-14 Formula (1-15) 59 84 5-15 Formula (2-8) 2 48 82 5-16 Formula (2-13)0.01 41 82 5-17 0.1 42 82 5-18 0.5 45 82 5-19 1 50 83 5-20 2 52 83 5-215 52 82 5-22 10 50 82 5-23 20 48 82 5-24 LiPF₆ EC + DMC — — 40 81 5-25Formula (18-1) 2 32 70 5-26 Formula (18-2) 2 25 58

TABLE 6 Anode active material: silicon Cyano Non-cyano CycleConservation compound compound retention retention Electrolyte ContentContent ratio ratio Example salt Solvent Type (wt %) Type (wt %) (%) (%)6-1 LiPF₆ EC + DMC Formula 2 Formula 0.2 68 88 (1-3) (3-1) 6-2 Formula69 88 (4-1) 6-3 Formula 68 92 (5-1) 6-4 LiPF₂O₂ 0.001 67 86 6-5 0.1 6887 6-6 0.2 70 88 6-7 1 70 88 6-8 2 70 88 6-9 Li₂PFO₃ 0.2 70 88 6-10Formula 2 Formula 0.2 54 84 (2-13) (3-1) 6-11 Formula 53 84 (4-1) 6-12Formula 54 86 (5-1) 6-13 LiPF₂O₂ 0.001 54 85 6-14 0.1 55 86 6-15 0.2 5686 6-16 1 56 86 6-17 2 56 86 6-18 Li₂PFO₃ 0.2 70 88 6-19 LiPF₆ EC + DMC— — Formula 0.2 38 81 (3-1) 6-20 Formula 38 81 (4-1) 6-21 Formula 40 83(5-1) 6-22 LiPF₂O₂ 38 81 6-23 Li₂PFO₃ 38 81

TABLE 7 Anode active material: silicon Cycle Conservation Cyano compoundretention retention Electrolyte Content ratio ratio Example salt SolventType (wt %) (%) (%) 7-1 LiPF₆ EC + DEC Formula (1-3) 2 64 86 7-2 EC +EMC 65 85 7-3 EC + PC + DMC 65 88 7-4 EC + VC 76 88 7-5 DMC FEC 80 877-6 t-DFEC 84 87 7-7 DFDMC 75 87 7-8 PRS 66 89 7-9 SCAH 68 88 7-10 PSAH68 90 7-11 EC + DEC Formula (2- 2 51 84 7-12 EC + EMC 13) 52 83 7-13EC + PC + DMC 51 85 7-14 EC + VC 74 85 7-15 DMC FEC 76 84 7-16 t-DFEC 8084 7-17 DFDMC 72 84 7-18 PRS 54 88 7-19 SCAH 54 87 7-20 PSAH 56 88 7-21LiPF₆ EC + VC — — 70 84 7-22 DMC FEC 60 81 7-23 t-DFEC 76 78 7-24 DFDMC68 80

TABLE 8 Anode active material: silicon Cycle Conservation Cyano compoundretention retention Content ratio ratio Example Electrolyte salt SolventType (wt %) (%) (%) 8-1 LiPF₆ LiBF₄ EC + DMC Formula (1-3) 2 65 87 8-2LiBOB 68 87 8-3 LiTFSI 65 88 8-4 LiPF₆ LiBF₄ EC + DMC Formula (2-13) 252 85 8-5 LiBOB 54 85 8-6 LiTFSI 52 86

Even when the metal-based material (silicon) was used as the anodeactive material, results similar to those of the examples (Tables 1 to4) in which the non-metal-based material (artificial graphite which is acarbon material) was used were obtained. Specifically, high cycleretention ratio and high conservation ratio were obtained when theelectrolytic solution included the cyano compound. Tendencies other thanthis were similar to those in the examples in which the non-metal-basedmaterial was used.

As can be seen from the results shown in Tables 1 to 8, superior batterycharacteristics were obtained when the electrolytic solution includedthe cyano compound.

(2) Examples of Second Embodiment

Next, various characteristics of secondary batteries of the secondembodiment were examined.

Examples 9-1 to 9-30

Lithium ion secondary batteries of a cylindrical type were fabricated byprocedures similar to those in Examples of the first embodiment exceptthat the following procedures were changed.

Upon fabricating the anode 22, a metal-based material (silicon) was usedas the anode active material.

For the sake of comparison, a non-metal-based material (artificialgraphite which is a carbon material) was used as the anode activematerial to form the anode active material layer 22B. In this example,90 parts by mass of the anode active material (artificial graphite) and10 parts by mass of the anode binder (PVDF) were mixed to obtain ananode mixture. Subsequently, the anode mixture was dispersed into anorganic solvent (NMP) to prepare paste cathode mixture slurry.Subsequently, the anode mixture slurry was coated uniformly on bothsurfaces of the strip-like anode current collector 22A with the use of acoating device, and was dried to form the anode active material layer22B. Lastly, the anode active material layer 22B was compression-moldedwith the use of a roll-pressing machine.

Upon preparing the electrolytic solution, the electrolyte salt (LiPF₆)was dissolved in the solvent (EC and DMC), and then the cyano compoundwas added thereto where appropriate as shown in Tables 9 and 10.

Various characteristics (cycle characteristics and conservationcharacteristics) of the secondary battery were examined by proceduressimilar to those in Examples of the first embodiment, and results shownin Tables 9 and 10 were obtained.

TABLE 9 Anode Electrolytic solution Cycle Anode Cyano compound retentionConservation active Content ratio retention ratio Example materialElectrolyte salt Solvent Type (wt %) (%) (%) 9-1 Silicon LiPF₆ EC + DMCFormula 5 65 83 (19-1) 9-2 Formula 0.01 42 82 9-3 (19-4) 0.1 45 83 9-40.5 50 83 9-5 1 55 84 9-6 2 60 85 9-7 5 80 85 9-8 10 80 84 9-9 20 75 829-10 Formula 5 66 83 (19-9) 9-11 Formula 5 55 85 (19-14) 9-12 Formula 560 84 (19-15) 9-13 Formula 5 58 86 (19-16) 9-14 Formula 5 62 84 (19-18)9-15 Formula 5 63 84 (19-20) 9-16 Formula 5 72 83 (20-1) 9-17 Formula0.01 42 82 9-18 (20-4) 0.1 45 83 9-19 0.5 50 83 9-20 1 55 83 9-21 2 5883 9-22 5 72 83 9-23 10 72 83 9-24 20 66 82 9-25 Formula 5 60 83 (20-13)9-26 Formula 5 72 84 (20-14)

TABLE 10 Electrolytic solution Cycle Anode Cyano compound retentionConservation Anode active Content ratio retention ratio Example materialElectrolyte salt Solvent Type (wt %) (%) (%) 9-27 Silicon LiPF₆ EC + DMC— — 40 81 9-28 Artificial LiPF₆ EC + DMC — — 90 81 9-29 graphite Formula5 88 81 (19-4) 9-30 Formula 5 85 81 (20-4)

In the examples where the non-metal-based material (artificial graphite)was used as the anode active material, favorable battery characteristicswere obtained irrespective of whether or not the cyano compound waspresent in the electrolytic solution. Specifically, when theelectrolytic solution included the cyano compound, cycle retention ratiowas decreased but conservation retention ratio was equivalent comparedto the examples in which the electrolytic solution did not include thecyano compound.

On the other hand, in the examples in which the metal-based material(silicon) was used, battery characteristics were largely varieddepending on whether or not the cyano compound was present in theelectrolytic solution. Specifically, when the electrolytic solutionincluded the cyano compound, cycle retention ratio and conservationretention ratio were both increased compared to the examples in whichthe electrolytic solution did not include the cyano compound.

The following tendencies can be seen from these results. In a case inwhich the non-metal-based material (carbon material) having lowreactivity is used as the anode active material, the non-metal-basedmaterial is less likely to influence chemical stability (or proceedingcharacteristics of a decomposition reaction) of the electrolyticsolution. Accordingly, high cycle retention ratio and high conservationretention ratio are intrinsically obtained with almost no influence ofwhether or not the cyano compound is present. Therefore, cycle retentionratio and conservation retention ratio are less likely to be improvedeven when the cyano compound is used. On the other hand, in a case inwhich a metal-based material having high reactivity is used, themetal-based material largely influences chemical stability of theelectrolytic solution. Accordingly, only low cycle retention ratio andlow conservation retention ratio are obtained when the cyano compound isnot used, and on the other hand, cycle retention ratio and conservationretention ratio are largely improved when the cyano compound is used.

In particular, in examples in which the metal-based material and thecyano compound were used, high cycle retention ratio and highconservation retention ratio were obtained when the content of the cyanocompound in the electrolytic solution was from 0.01 wt % to 20 wt % bothinclusive.

Examples 10-1 to 10-26

As shown in Table 11, secondary batteries were fabricated by proceduressimilar to those in Examples 9-1 to 9-27 except that the composition ofthe solvent was changed as in Examples of the first embodiment.

TABLE 11 Electrolytic solution Anode Cyano Cycle Conservation Anodecompound retention retention active Electrolyte Content ratio ratioExample material salt Solvent Type (wt %) (%) (%) 10-1 Silicon LiPF₆EC + DEC Formula 5 80 88 10-2 EC + EMC (19-4) 80 87 10-3 EC + PC + DMC80 90 10-4 EC + VC 85 86 10-5 DEC FEC 90 85 10-6 t-DFEC 92 85 10-7 DFDMC90 85 10-8 PRS 81 92 10-9 SCAH 81 90 10-10 PSAH 84 94 10-11 EC + DECFormula 5 72 85 10-12 EC + EMC (20-4) 72 86 10-13 EC + PC + DMC 72 8610-14 EC + VC 78 86 10-15 DEC FEC 80 85 10-16 t-DFEC 84 85 10-17 DFDMC80 85 10-18 PRS 73 90 10-19 SCAH 74 88 10-20 PSAH 76 92 10-21 SiliconLiPF₆ EC + VC — — 70 84 10-22 DEC FEC 60 81 10-23 t-DFEC 76 78 10-24DFDMC 68 80 10-25 PRS 42 84 10-26 PSAH 44 84

Even when the composition of the solvent was changed, high cycleretention ratio and high conservation retention ratio were obtained whenthe electrolytic solution included the cyano compound.

Examples 11-1 to 11-6

As shown in Table 12, secondary batteries were fabricated by proceduressimilar to those in Examples 9-1 to 9-26 except that the composition ofthe electrolyte salt was changed as in Examples of the first embodiment.

TABLE 12 Anode Electrolytic solution Cycle Anode Cyano compoundretention Conservation active Content ratio retention ratio Examplematerial Electrolyte salt Solvent Type (wt %) (%) (%) 11-1 Silicon LiPF₆LiBF₄ EC + DMC Formula 5 80 90 11-2 LiBOB (19-4) 80 90 11-3 LiTFSI 80 9011-4 LiPF₆ LiBF₄ EC + DMC Formula 5 73 88 11-5 LiBOB (20-4) 72 87 11-6LiTFSI 72 88

Even when the composition of the electrolyte salt was changed, highcycle retention ratio and high conservation retention ratio wereobtained when the electrolytic solution included the cyano compound. Inparticular, conservation retention ratio was further increased when theelectrolytic solution included LiBF₄ or the like.

As can be seen from the results shown in Tables 9 to 12, superiorbattery characteristics were obtained when the anode included themetal-based material and the electrolytic solution included the cyanocompound.

(3) Examples of Third Embodiment

Next, various characteristics of the secondary battery of the thirdembodiment were examined.

Examples 12-1 to 12-50

Lithium ion secondary batteries of a cylindrical type were fabricated byprocedures similar to those in Examples of the first embodiment exceptthat the following procedures were changed.

Upon preparing the electrolytic solution, the electrolyte salt (LiPF₆)was dissolved in the solvent (EC and DMC) and then, the cyano compoundand the non-cyano compound were added thereto where appropriate as shownin Tables 13 to 15.

Various characteristics (cycle characteristics and load characteristics)of the secondary battery were examined, and the results shown in Tables13 to 15 were obtained.

Upon examining cycle characteristics, the secondary battery was chargedand discharged for two cycles in a high temperature environment (45°C.), and discharge capacity thereof at the second cycle was measured.Subsequently, the secondary battery was charged and dischargedrepeatedly in the same environment until the total number of cyclereached 300, and then, the discharge capacity thereof at the 300th cyclewas measured. Based on this result, capacity retention ratio(%)=(discharge capacity at the 300th cycle/discharge capacity at the 2ndcycle)×100 was calculated. The charge and discharge conditions weresimilar to those in Examples of the first embodiment.

Upon examining load characteristics, the secondary battery was chargedin an ambient temperature environment (23° C.), and the secondarybattery in the charged state was cooled in a thermostat bath (0° C.) for2 hours. The secondary battery was charged at a current of 0.5 C untilthe voltage reached the upper limit voltage of 4.2 V, and then, thesecondary battery was charged at a voltage of 4.2 V for 4 hours. “0.5 C”refers to a current value with which the battery capacity is completelydischarged in 2 hours. Subsequently, the secondary battery wasdischarged at electric power of 15 W until the voltage reached the finalvoltage of 3.0 V. At this time, voltages were measured from thebeginning of discharge to the time which was 5 minutes after thebeginning of discharge, and the minimum value (minimum voltage (V))thereof was measured.

TABLE 13 Anode active material: artificial graphite Cyano Non cyanoCapacity compound compound retention Minimum Electrolyte Content Contentratio voltage Example salt Solvent Type (wt %) Type (wt %) (%) (V) 12-1LiPF₆ EC + Formula 0.01 LiPF₂O₂ 0.2 80 3.45 12-2 DMC (19-1) 0.1 81 3.4512-3 0.5 83 3.52 12-4 1 85 3.52 12-5 2 88 3.51 12-6 5 88 3.51 12-7 10 863.5 12-8 20 85 3.5 12-9 Formula 2 LiPF₂O₂ 0.2 85 3.5 (19-4) 12-10Formula 84 3.5 (19-9) 12-11 Formula 86 3.5 (19-14) 12-12 Formula 84 3.5(19-15) 12-13 Formula 85 3.5 (19-16) 12-14 Formula 85 3.5 (19-18) 12-15Formula 84 3.5 (19-20) 12-16 Formula 2 LiPF₂O₂ 0.001 80 3.45 12-17(19-1) 0.1 85 3.48 12-18 1 88 3.5 12-19 2 87 3.48 12-20 Formula 2Formula 0.2 86 3.5 (19-1) (3-1) 12-21 Formula 86 3.5 (4-1) 12-22 Formula88 3.58 (5-1) 12-23 Li₂PFO₃ 87 3.51

TABLE 14 Anode active material: artificial graphite Cyano Non-cyanoCapacity compound compound retention Minimum Electrolyte Content Contentratio voltage Example salt Solvent Type (wt %) Type (wt %) (%) (V) 12-24LiPF₆ EC + Formula 2 LiPF₂O₂ 0.2 84 3.5 DMC (20-1) 12-25 Formula 0.01LiPF₂O₂ 0.2 80 3.45 12-26 (20-4) 0.1 82 3.45 12-27 0.5 83 3.52 12-28 185 3.52 12-29 2 85 3.51 12-30 5 85 3.51 12-31 10 84 3.5 12-32 20 83 3.512-33 Formula 2 LiPF₂O₂ 0.2 84 3.5 (20-13) 12-34 Formula 83 3.5 (20-14)12-35 Formula 2 LiPF₂O₂ 0.001 80 3.45 12-36 (20-4) 0.1 83 3.48 12-37 184 3.5 12-38 2 84 3.48 12-39 Formula 2 Formula 0.2 85 3.5 (20-4) (3-1)12-40 Formula 84 3.5 (4-1) 12-41 Formula 86 3.58 (5-1) 12-42 Li₂PFO₃ 843.51

TABLE 15 Anode active material: artificial graphite Cyano Non-cyanoCapacity compound compound retention Minimum Electrolyte Content Contentratio voltage Example salt Solvent Type (wt %) Type (wt %) (%) (V) 12-43LiPF₆ EC + — — — — 65 3.42 12-44 DMC Formula 2 — — 62 3.42 (19-1) 12-45Formula 62 3.42 (20-4) 12-46 — — Formula 0.2 77 3.43 (3-1) 12-47 Formula76 3.42 (4-1) 12-48 Formula 78 3.45 (5-1) 12-49 LiPF₂O₂ 78 3.44 12-50Li₂PFO₃ 77 3.44

In the examples in which the carbon material (artificial graphite) wasused as the anode active material, high capacity retention ratio wasobtained and the minimum voltage was increased when the electrolyticsolution includes both the cyano compound and the non-cyano compound.

In detail, an example (Example 12-43) in which the cyano compound northe non-cyano compound was used was used as a reference. In the examples(Examples 12-44 and 12-45) in which only the cyano compound was used,the minimum voltage was equivalent but capacity retention ratio wasdecreased. On the other hand, in the examples (Examples 12-46 to 12-50)in which only the non-cyano compound was used, capacity retention ratiowas increased and the minimum voltage was slightly increased with sometypes of non-cyano compound. Based on these results, it can be expectedthat, when the cyano compound and the non-cyano compound are used incombination, capacity retention ratio is increased but the value thereofis lower than that in the case in which only the non-cyano compound isused, and the minimum voltage is only slightly increased with some typesof non-cyano compound.

However, when the cyano compound and the non-cyano compound were used incombination (Examples 12-1 to 12-42), capacity retention ratio wasremarkably increased and the value thereof was much larger than that inthe examples in which only the non-cyano compound was used. Further, theminimum voltage was increased and the value thereof was larger than thatin the examples in which only the non-cyano compound was used. As can beseen from these results, when the cyano compound and the non-cyanocompound are used in combination, a decomposition reaction of theelectrolytic solution is specifically suppressed due to the synergeticfunction of the both compounds. Specifically, influence of whether ornot the respective cyano compound and non-cyano compound are present oncapacity retention ratio and on minimum voltage were actually examined,and it was found that, by using the cyano compound and the non-cyanocompound in combination, advantageous tendencies were obtained that wereunpredictable from the tendencies obtained in the case in which only oneof the compounds was solely used.

In particular, high capacity retention ratio and high minimum voltagewere obtained when the content of the cyano compound was from 0.01 wt %to 20 wt % both inclusive or when the content of the non-cyano compoundwas from 0.001 wt % to 2 wt % both inclusive. In this case, morefavorable results were obtained when the content of the cyano compoundwas from 0.5 wt % to 20 wt % both inclusive or when the content of thenon-cyano compound was from 0.1 wt % to 2 wt % both inclusive.

Examples 13-1 to 13-24

As shown in Table 16, secondary batteries were fabricated by proceduressimilar to those in Examples 12-1 to 12-50 except that the compositionof the solvent was changed as in Examples of the first embodiment, andvarious characteristics thereof were examined.

TABLE 16 Anode active material: artificial graphite Cyano Non-cyanoCapacity compound compound retention Electrolyte Content Content ratioMinimum Example salt Solvent Type (wt %) Type (wt %) (%) voltage (V)13-1  LiPF₆ EC + DEC Formula 2 LiPF₂O₂ 0.2 88 3.55 13-2  EC + EMC (19-1)88 3.55 13-3  EC + PC + DMC 87 3.58 13-4  EC + VC 87 3.48 13-5  DEC FEC92 3.45 13-6  t-DFEC 90 3.45 13-7  DFDMC 88 3.45 13-8  PRS 90 3.62 13-9 SCAH 90 3.48 13-10 PSAH 92 3.65 13-11 EC + DEC Formula 2 LiPF₂O₂ 0.2 853.55 13-12 EC + EMC (20-4) 86 3.55 13-13 EC + PC + DMC 87 3.58 13-14EC + VC 87 3.48 13-15 DEC FEC 90 3.45 13-16 t-DFEC 88 3.45 13-17 DFDMC87 3.45 13-18 PRS 88 3.62 13-19 SCAH 90 3.48 13-20 PSAH 90 3.65 13-21EC + VC — — — — 80 3.2 13-22 DEC FEC 79 3.36 13-23 t-DFEC 79 3.32 13-24DFDMC 78 3.33

Even when the composition of the solvent was changed, high cycleretention ratio and high minimum voltage were obtained when theelectrolytic solution included the cyano compound and the non-cyanocompound. In particular, with some composition of the solvent, cycleretention ratio and minimum voltage were further increased.

Examples 14-1 to 14-6

As shown in Table 17, secondary batteries were fabricated by proceduressimilar to those in Examples 12-1 to 12-50 except that the compositionof the electrolyte salt was changed as in Examples of the firstembodiment, and various characteristics thereof were examined.

TABLE 17 Anode active material: artificial graphite Cyano Non-cyanoCapacity compound compound retention Content Content ratio MinimumExample Electrolyte salt Solvent Type (wt %) Type (wt %) (%) voltage (V)14-1 LiPF₆ LiBF₄ EC + Formula 2 LiPF₂O₂ 0.2 89 3.52 14-2 LiBOB DMC(19-1) 89 3.52 14-3 LiTFSI 89 3.53 14-4 LiPF₆ LiBF₄ Formula 2 86 3.5214-5 LiBOB (20-4) 86 3.52 14-6 LiTFSI 86 3.53

Even when the composition of the electrolyte salt was changed, highcycle retention ratio and high minimum voltage were obtained when theelectrolytic solution included the cyano compound and the non-cyanocompound. In particular, cycle retention ratio and minimum voltage werefurther increased when the electrolytic solution included LiBF₄ or thelike.

Examples 15-1 to 15-50, 16-1 to 16-24, and 17-1 to 17-6

As shown in Tables 18 to 20, secondary batteries were fabricated byprocedures similar to those in Examples 12-1 to 12-50, 13-1 to 13-24,and 14-1 to 14-6 except that a metal-based material (silicon) was usedas the anode active material, and various characteristics thereof wereexamined. Procedures of fabricating the anode 22 were similar to thosein Examples of the first embodiment.

TABLE 18 Anode active material: silicon Cyano Non-cyano Capacitycompound compound retention Electrolyte Content Content ratio MinimumExample salt Solvent Type (wt %) Type (wt %) (%) voltage (V) 15-1 LiPF₆EC + Formula 0.01 LiPF₂O₂ 0.2 41 3.48 15-2 DMC (19-1) 0.1 42 3.49 15-30.5 44 3.49 15-4 1 48 3.49 15-5 2 50 3.5 15-6 5 50 3.5 15-7 10 47 3.515-8 20 46 3.48 15-9 Formula 2 LiPF₂O₂ 0.2 70 3.5 (19-4) 15-10 Formula64 3.39 (19-9) 15-11 Formula 64 3.49 (19-14) 15-12 Formula 58 3.49(19-15) 15-13 Formula 65 3.5 (19-16) 15-14 Formula 60 3.49 (19-18) 15-15Formula 61 3.49 (19-20) 15-16 Formula 2 LiPF₂O₂ 0.001 42 3.48 15-17(19-1) 0.1 44 3.49 15-18 1 50 3.49 15-19 2 50 3.49 15-20 Formula 2Formula 0.2 48 3.49 (19-1) (3-1) 15-21 Formula 48 3.49 (4-1) 15-22Formula 50 3.51 (5-1) 15-23 Li₂PFO₃ 49 3.49

TABLE 19 Anode active material: silicon Cyano Non-cyano Capacitycompound compound retention Electrolyte Content Content ratio MinimumExample salt Solvent Type (wt %) Type (wt %) (%) voltage (V) 15-24 LiPF₆EC + Formula 2 LiPF₂O₂ 0.2 46 3.48 DMC (20-1) 15-25 Formula 0.01 LiPF₂O₂0.2 42 3.48 15-26 (20-4) 0.1 42 3.48 15-27 0.5 44 3.48 15-28 1 47 3.4815-29 2 48 3.49 15-30 5 48 3.49 15-31 10 46 3.49 15-32 20 44 3.49 15-33Formula 2 LiPF₂O₂ 0.2 48 3.49 (20-13) 15-34 Formula 56 3.49 (20-14)15-35 Formula 2 LiPF₂O₂ 0.001 46 3.48 15-36 (20-4) 0.1 48 3.49 15-37 148 3.49 15-38 2 48 3.49 15-39 Formula 2 Formula (3- 0.2 46 3.5 (20-4) 1)15-40 Formula (4- 46 3.5 1) 15-41 Formula (5- 47 3.5 1) 15-42 Li₂PFO₃ 483.51

TABLE 20 Anode active material: silicon Cyano Capacity compoundNon-cyano compound retention Electrolyte Content Content ratio MinimumExample salt Solvent Type (wt %) Type (wt %) (%) voltage (V) 15-43 LiPF₆EC + — — — — 40 3.42 15-44 DMC Formula 2 — — 32 3.32 (19-1) 15-45Formula 25 3.33 (20-4) 15-46 — — Formula (3-1) 0.2 38 3.43 15-47 Formula(4-1) 38 3.42 15-48 Formula (5-1) 40 3.44 15-49 LiPF₂O₂ 38 3.43 15-50Li₂PFO₃ 38 3.43

TABLE 21 Anode active material: silicon Cyano Non-cyano Capacitycompound compound retention Electrolyte Content Content ratio MinimumExample salt Solvent Type (wt %) Type (wt %) (%) voltage (V) 16-1 LiPF₆EC + DEC Formula 2 LiPF₂O₂ 0.2 49 3.49 16-2 EC + EMC (19-1) 50 3.5 16-3EC + PC + DMC 50 3.53 16-4 EC + VC 74 3.49 16-5 DEC FEC 74 3.49 16-6t-DFEC 76 3.5 16-7 DFDMC 73 3.5 16-8 PRS 56 3.53 16-9 SCAH 58 3.49 16-10PSAH 60 3.55 16-11 EC + DEC Formula 2 LiPF₂O₂ 0.2 47 3.49 16-12 EC + EMC(20-4) 48 3.5 16-13 EC + PC + DMC 48 3.52 16-14 EC + VC 72 3.49 16-15DEC FEC 74 3.5 16-16 t-DFEC 78 3.49 16-17 DFDMC 70 3.5 16-18 PRS 52 3.5216-19 SCAH 55 3.5 16-20 PSAH 58 3.54 16-21 EC + VC — — — — 70 3.33 16-22DEC FEC 60 3.4 16-23 t-DFEC 76 3.38 16-24 DFDMC 68 3.38

TABLE 22 Anode active material: silicon Cyano Non-cyano Capacitycompound compound retention Minimum Content Content ratio voltageExample Electrolyte salt Solvent Type (wt %) Type (wt %) (%) (V) 17-1LiPF₆ LiBF₄ EC + Formula 2 LiPF₂O₂ 0.2 51 3.5 17-2 LiBOB DMC (19-1) 563.46 17-3 LiTFSI 52 3.5 17-4 LiPF₆ LiBF₄ Formula 2 52 3.5 17-5 LiBOB(20-4) 55 3.46 17-6 LiTFSI 52 3.5

Even when the metal-based material (silicon) was used as the anodeactive material, results similar to those in the examples (Tables 13 to17) in which the non-metal-based material (artificial graphite which isa carbon material) was used were obtained. Specifically, high cycleretention ratio and high minimum voltage were obtained when theelectrolytic solution included both the cyano compound and the non-cyanocompound. Tendencies other than this were similar to those in the casesin which the non-metal-based material was used.

As can be seen from the results shown in Tables 13 to 22, superiorbattery characteristics were obtained when the electrolytic solutionincluded both the cyano compound and the non-cyano compound.

Hereinabove, the present application has been described with referenceto the preferred embodiments and Examples. However, the presentapplication is not limited to the examples described in the preferredembodiments and Examples and may be variously modified. For example,description has been given with referring to the examples in which thebattery has a cylindrical type or a laminated film type batterystructure and has a battery device of a spirally wound structure.However, the secondary battery of the present application is not limitedthereto, and may be similarly applicable, for example, to a battery thathas other battery structure such as a square type, a coin type, and abutton type and to a battery that has a battery device of otherstructure such as a lamination structure.

The case in which Li is used as the electrode reactant has beendescribed. However, this is not limitative. The electrode reactant maybe, for example, other Group 1 elements such as Na and K, Group 2elements such as Mg and Ca, or other light metal such as Al. Since theeffects of the present application may be obtained irrespective ofelectrode reactant type, similar effects are obtainable even if the typeof the electrode reactant is changed.

Further, the content of the cyano compound has been described with anappropriate range resulted from the results of Examples. However, thedescription does not necessarily deny a possibility that the contentthereof is out of the above-described range. In other words, theabove-described appropriate range is merely a range especiallypreferable in obtaining the effects of the present application.Therefore, the content may be out of the above-described range in somedegree as long as the effects of the present application are obtained.The same is applicable to the content of the non-cyano compound.

It is possible to achieve at least the following configurations from theabove-described example embodiments of the disclosure.

1. First Embodiment/Electrolytic Solution and Secondary Battery (cyanocompound: the number of cyano group is limited)

(1) A secondary battery including:

a cathode;

an anode; and

an electrolytic solution including a cyano compound, the cyano compoundincluding a compound represented by a following Formula (1), a compoundrepresented by a following Formula (2), or both,

where R1 and R2 are each one of a saturated hydrocarbon group, anunsaturated hydrocarbon group, an oxygen-containing saturatedhydrocarbon group, a cyano-group-containing group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another, and the R1, the R2, or both includethe cyano-group-containing group; a cyano group in thecyano-group-containing group is bonded to an oxygen atom (O) at aterminal of a —O—C(═O)—O— bond with one or more carbon atoms (C) inbetween; (A) when one of the R1 and the R2 does not include thecyano-group-containing group but includes an unsaturated carbon bond andthe other of the R1 and the R2 includes the cyano-group-containinggroup, number of the cyano group in the other of the R1 and the R2 isone or larger; (B) when one of the R1 and the R2 include neither thecyano-group-containing group nor the unsaturated carbon bond and theother of the R1 and the R2 includes the cyano-group-containing group andthe unsaturated carbon bond, the number of the cyano group in the otherof the R1 and the R2 is one or larger; and (C) when one of the R1 andthe R2 include neither the cyano-group-containing group nor theunsaturated carbon bond and the other of the R1 and the R2 includes thecyano-group-containing group but does not include the unsaturated carbonbond, the number of the cyano group in the other of the R1 and the R2 istwo or larger,

where R3 is one of a saturated hydrocarbon group, an unsaturatedhydrocarbon group, an oxygen-containing saturated hydrocarbon group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another; R4 is one ofa cyano-group-containing group, halogenated groups thereof, and groupseach obtained by bonding two or more of the foregoing groups to oneanother; a cyano group in the cyano-group-containing group is bonded toan oxygen atom at a terminal of a —C(═O)—O-bond with one or more carbonatoms in between; (D) when the R3 includes an unsaturated carbon bond,number of the cyano group in the R4 is one or larger; (E) when the R3does not include the unsaturated carbon bond and the R4 includes theunsaturated carbon bond, the number of the cyano group in the R4 is oneor larger; and (F) when the R3 does not include the unsaturated carbonbond and the R4 does not include the unsaturated carbon bond, the numberof the cyano group in the R4 is two or larger.(2) The secondary battery according to (1), wherein thecyano-group-containing group is one of a group obtained by substitutingeach of part or all of hydrogen groups in a saturated hydrocarbon groupby a cyano group and a group obtained by substituting each of part orall of hydrogen groups in an unsaturated hydrocarbon group by a cyanogroup.(3) The secondary battery according to (2), wherein

the saturated hydrocarbon group is an alkyl group with carbon numberfrom 1 to 12 both inclusive, and

the unsaturated hydrocarbon group is an aryl group with carbon numberfrom 6 to 18 both inclusive.

(4) The secondary battery according to any one of (1) to (3), wherein

the saturated hydrocarbon group is one of an alkyl group with carbonnumber from 1 to 12 both inclusive and a cycloalkyl group with carbonnumber from 3 to 18 both inclusive,

the unsaturated hydrocarbon group is one of an alkenyl group with carbonnumber from 2 to 12 both inclusive, an alkynyl group with carbon numberfrom 2 to 12 both inclusive, and an aryl group with carbon number from 6to 18 both inclusive,

the oxygen-containing saturated hydrocarbon group is an alkoxy groupwith carbon number from 1 to 12 both inclusive, and

the halogenated groups each include, as a halogen group, one or more ofa fluorine group, a chlorine group, a bromine group, and an iodinegroup.

(5) The secondary battery according to any one of (1) to (4), wherein

the compound represented by the Formula (1) is one or more of compoundsrepresented by following Formula (1-1) to Formula (1-25), and thecompound represented by the Formula (2) is one or more of compoundsrepresented by following Formula (2-1) to Formula (2-21).

(6) The secondary battery according to any one of (1) to (5), wherein acontent of the cyano compound in the electrolytic solution is from about0.01 weight percent to about 20 weight percent both inclusive.(7) The secondary battery according to any one of (1) to (6), wherein

the electrolytic solution includes a non-cyano compound, and

the non-cyano compound includes one or more of a compound represented bya following Formula (3), a compound represented by a following Formula(4), a compound represented by a following Formula (5), a compoundrepresented by a following Formula (6), and a compound represented by afollowing Formula (7),

where R11 and R13 are each one of a monovalent hydrocarbon group, amonovalent oxygen-containing hydrocarbon group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another; and R12 is one of a divalenthydrocarbon group and halogenated groups thereof,

where R14 and R16 are each one of a monovalent hydrocarbon group, amonovalent oxygen-containing hydrocarbon group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another; R15 is one of a divalenthydrocarbon group and halogenated groups thereof; and n is an integerthat is 1 or larger,

where R17 and R19 are each one of a monovalent hydrocarbon group, amonovalent oxygen-containing hydrocarbon group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another; and R18 is one of a divalenthydrocarbon group and halogenated groups thereof.

LiPF₂O₂  (6)

Li₂PFO₃  (7)

(8) The secondary battery according to (7), wherein

the monovalent hydrocarbon group and the monovalent oxygen-containinghydrocarbon group include an alkyl group with carbon number from 1 to 12both inclusive, an alkenyl group with carbon number from 2 to 12 bothinclusive, an alkynyl group with carbon number from 2 to 12 bothinclusive, an aryl group with carbon number from 6 to 18 both inclusive,a cycloalkyl group with carbon number from 3 to 18 both inclusive, andan alkoxy group with carbon number from 1 to 12 both inclusive,

the divalent hydrocarbon group is one of an alkylene group with carbonnumber from 1 to 12 both inclusive, an alkenylene group with carbonnumber from 2 to 12 both inclusive, an alkynylene group with carbonnumber from 2 to 12 both inclusive, an arylene group with carbon numberfrom 6 to 18 both inclusive, a cycloalkylene group with carbon numberfrom 3 to 18 both inclusive, groups each obtained by bonding two or moreof the foregoing groups to one another, and groups each including one ormore of the foregoing groups and an ether bond (—O—), and

the halogenated group includes, as a halogen group, one or more of afluorine group, a chlorine group, a bromine group, and an iodine group.

(9) The secondary battery according to (7) or (8), wherein

the compound represented by the Formula (3) is one or more of compoundsrepresented by following Formula (3-1) to Formula (3-12),

the compound represented by the Formula (4) is one or more of compoundsrepresented by following Formula (4-1) to Formula (4-17), and

the compound represented by the Formula (5) is one or more of compoundsrepresented by following Formula (5-1) to Formula (5-9).

(10) The secondary battery according to any one of (7) to (9), wherein acontent of the non-cyano compound in the electrolytic solution is fromabout 0.001 weight percent to about 2 weight percent both inclusive.(11) The secondary battery according to any one of (1) to (10), whereinthe secondary battery is a lithium secondary battery.(12) An electrolytic solution including

a cyano compound including a compound represented by a following Formula(1), a compound represented by a following Formula (2), or both,

where R1 and R2 are each one of a saturated hydrocarbon group, anunsaturated hydrocarbon group, an oxygen-containing saturatedhydrocarbon group, a cyano-group-containing group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another, and the R1, the R2, or both includethe cyano-group-containing group; a cyano group in thecyano-group-containing group is bonded to an oxygen atom (O) at aterminal of a —O—C(═O)—O— bond with one or more carbon atoms (C) inbetween; (A) when one of the R1 and the R2 does not include thecyano-group-containing group but includes an unsaturated carbon bond andthe other of the R1 and the R2 includes the cyano-group-containinggroup, number of the cyano group in the other of the R1 and the R2 isone or larger; (B) when one of the R1 and the R2 include neither thecyano-group-containing group nor the unsaturated carbon bond and theother of the R1 and the R2 includes the cyano-group-containing group andthe unsaturated carbon bond, the number of the cyano group in the otherof the R1 and the R2 is one or larger; and (C) when one of the R1 andthe R2 include neither the cyano-group-containing group nor theunsaturated carbon bond and the other of the R1 and the R2 includes thecyano-group-containing group but does not include the unsaturated carbonbond, the number of the cyano group in the other of the R1 and the R2 istwo or larger,

where R3 is one of a saturated hydrocarbon group, an unsaturatedhydrocarbon group, an oxygen-containing saturated hydrocarbon group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another; R4 is one ofa cyano-group-containing group, halogenated groups thereof, and groupseach obtained by bonding two or more of the foregoing groups to oneanother; a cyano group in the cyano-group-containing group is bonded toan oxygen atom at a terminal of a —C(═O)—O— bond with one or more carbonatoms in between; (D) when the R3 includes an unsaturated carbon bond,number of the cyano group in the R4 is one or larger; (E) when the R3does not include the unsaturated carbon bond and the R4 includes theunsaturated carbon bond, the number of the cyano group in the R4 is oneor larger; and (F) when the R3 does not include the unsaturated carbonbond and the R4 does not include the unsaturated carbon bond, the numberof the cyano group in the R4 is two or larger.(13) A battery pack including:

the secondary battery according to any one of (1) to (11);

a control section controlling a used state of the secondary battery; and

a switch section switching the used state of the secondary batteryaccording to an instruction of the control section.

(14) An electric vehicle including:

the secondary battery according to any one of (1) to (11);

a conversion section converting electric power supplied from thesecondary battery into drive power;

a drive section operating according to the drive power; and

a control section controlling a used state of the secondary battery.

(15) An electric power storage system including:

the secondary battery according to any one of (1) to (11);

one or more electric devices supplied with electric power from thesecondary battery; and

a control section controlling the supplying of the electric power fromthe secondary battery to the one or more electric devices.

(16) An electric power tool including:

the secondary battery according to any one of (1) to (11); and

a movable section supplied with electric power from the secondarybattery.

(17) An electronic apparatus including

the secondary battery according to any one of (1) to (11) as an electricpower supply source.

2. Second Embodiment/Secondary Battery (cyano compound: the number ofcyano compound is not limited+metal-based material)

(1) A secondary battery including:

a cathode;

an anode including a metal-based material that includes silicon (Si),tin (Sn), or both as constituent elements; and

an electrolytic solution including a cyano compound, the cyano compoundincluding a compound represented by a following Formula (19), a compoundrepresented by a following Formula (20), or both,

where R5 and R6 are each one of a hydrocarbon group, anoxygen-containing hydrocarbon group, a cyano-group-containing group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another, and the R5,the R6, or both include the cyano-group-containing group; a cyano groupin the cyano-group-containing group in the R5, the R6, or both is bondedto an oxygen atom (O) at a terminal of a —O—C(═O)—O— bond with one ormore carbon atoms (C) in between,

where R7 is one of a hydrocarbon group, an oxygen-containing hydrocarbongroup, a cyano-group-containing group, halogenated groups of theforegoing groups, and groups each obtained by bonding two or more of theforegoing groups to one another; R8 is one of a cyano-group-containinggroup, halogenated groups thereof, and groups each obtained by bondingtwo or more of the foregoing groups to one another; a cyano group in thecyano-group-containing group in R8 is bonded to an oxygen atom at aterminal of a —C(═O)—O— bond with one or more carbon atoms in between.(2) The secondary battery according to (1), wherein thecyano-group-containing group is a group obtained by substituting each ofpart or all of hydrogen groups in a hydrocarbon group by a cyano group.(3) The secondary battery according to (2), wherein the hydrocarbongroup is one of an alkyl group with carbon number from 1 to 12 bothinclusive and an aryl group with carbon number from 6 to 18 bothinclusive.(4) The secondary battery according to any one of (1) to (3), wherein

the hydrocarbon group is one of an alkyl group with carbon number from 1to 12 both inclusive, an alkenyl group with carbon number from 2 to 12both inclusive, an alkynyl group with carbon number from 2 to 12 bothinclusive, an aryl group with carbon number from 6 to 18 both inclusive,and a cycloalkyl group with carbon number from 3 to 18 both inclusive,

the oxygen-containing saturated hydrocarbon group is an alkoxy groupwith carbon number from 1 to 12 both inclusive, and

the halogenated groups each include, as a halogen group, one or more ofa fluorine group, a chlorine group, a bromine group, and an iodinegroup.

(5) The secondary battery according to any one of (1) to (4), wherein

the compound represented by the Formula (19) is one or more of compoundsrepresented by following Formula (19-1) to Formula (19-31), and

the compound represented by the Formula (20) is one or more of compoundsrepresented by following Formula (20-1) to Formula (20-28).

(6) The secondary battery according to any one of (1) to (5), wherein acontent of the cyano compound in the electrolytic solution is from about0.01 weight percent to about 20 weight percent both inclusive.(7) The secondary battery according to any one of (1) to (6), wherein

the metal-based material is one or more of a simple substance, an alloy,and a compound of Si, and a simple substance, an alloy, and a compoundof Sn.

(8) The secondary battery according to any one of (1) to (7), whereinthe secondary battery is a lithium secondary battery.(9) A battery pack including:

the secondary battery according to any one of (1) to (8);

a control section controlling a used state of the secondary battery; and

a switch section switching the used state of the secondary batteryaccording to an instruction of the control section.

(10) An electric vehicle including:

the secondary battery according to any one of (1) to (8);

a conversion section converting electric power supplied from thesecondary battery into drive power;

a drive section operating according to the drive power; and

a control section controlling a used state of the secondary battery.

(11) An electric power storage system including:

the secondary battery according to any one of (1) to (8);

one or more electric devices supplied with electric power from thesecondary battery; and

a control section controlling the supplying of the electric power fromthe secondary battery to the one or more electric devices.

(12) An electric power tool including:

the secondary battery according to any one of (1) to (8); and

a movable section supplied with electric power from the secondarybattery.

(13) An electronic apparatus including

the secondary battery according to any one of (1) to (8) as an electricpower supply source.

3. Third Embodiment/Secondary Battery (cyano compound: the number ofcyano compound is not limited+non-cyano compound)

(1) A secondary battery including:

a cathode;

an anode; and

an electrolytic solution including a cyano compound and a non-cyanocompound, the cyano compound including a compound represented by afollowing Formula (19), a compound represented by a following Formula(20), or both, and the non-cyano compound including one of a compoundrepresented by a following Formula (3), a compound represented by afollowing Formula (4), a compound represented by a following Formula(5), a compound represented by a following Formula (6), and a compoundrepresented by a following Formula (7)

where R5 and R6 are each one of a hydrocarbon group, anoxygen-containing hydrocarbon group, a cyano-group-containing group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another, and the R5,the R6, or both include the cyano-group-containing group; a cyano groupin the cyano-group-containing group in the R5, the R6, or both is bondedto an oxygen atom (O) at a terminal of a —O—C(═O)—O— bond with one ormore carbon atoms (C) in between,

where R7 is one of a hydrocarbon group, an oxygen-containing hydrocarbongroup, a cyano-group-containing group, halogenated groups of theforegoing groups, and groups each obtained by bonding two or more of theforegoing groups to one another; R8 is one of a cyano-group-containinggroup, halogenated groups thereof, and groups each obtained by bondingtwo or more of the foregoing groups to one another; a cyano group in thecyano-group-containing group in R8 is bonded to an oxygen atom at aterminal of a —C(═O)—O— bond with one or more carbon atoms in between,

where R11 and R13 are each one of a monovalent hydrocarbon group, amonovalent oxygen-containing hydrocarbon group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another; and R12 is one of a divalenthydrocarbon group and halogenated groups thereof,

where R14 and R16 are each one of a monovalent hydrocarbon group, amonovalent oxygen-containing hydrocarbon group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another; R15 is one of a divalenthydrocarbon group and halogenated groups thereof; and n is an integerthat is 1 or larger,

where R17 and R19 are each one of a monovalent hydrocarbon group, amonovalent oxygen-containing hydrocarbon group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another; and R18 is one of a divalenthydrocarbon group and halogenated groups thereof.

LiPF₂O₂  (6)

Li₂PFO₃  (7)

(2) The secondary battery according to (1), wherein thecyano-group-containing group is a group obtained by substituting each ofpart or all of hydrogen groups in a hydrocarbon group by a cyano group.(3) The secondary battery according to (2), wherein

the hydrocarbon group is one of an alkyl group with carbon number from 1to 12 both inclusive and an aryl group with carbon number from 6 to 18both inclusive.

(4) The secondary battery according to any one of (1) to (3), wherein

in the Formula (19) and the Formula (20),

the hydrocarbon group is one of an alkyl group with carbon number from 1to 12 both inclusive, an alkenyl group with carbon number from 2 to 12both inclusive, an alkynyl group with carbon number from 2 to 12 bothinclusive, an aryl group with carbon number from 6 to 18 both inclusive,and a cycloalkyl group with carbon number from 3 to 18 both inclusive,

the oxygen-containing hydrocarbon group is an alkoxy group with carbonnumber from 1 to 12 both inclusive, and

the halogenated groups each include, as a halogen group, one or more ofa fluorine group, a chlorine group, a bromine group, and an iodinegroup.

(5) The secondary battery according to any one of (1) to (4), wherein

in the Formula (3) to the Formula (5),

the monovalent hydrocarbon group is one of an alkyl group with carbonnumber from 1 to 12 both inclusive, an alkenyl group with carbon numberfrom 2 to 12 both inclusive, an alkynyl group with carbon number from 2to 12 both inclusive, an aryl group with carbon number from 6 to 18 bothinclusive, and a cycloalkyl group with carbon number from 3 to 18 bothinclusive,

the monovalent oxygen-containing hydrocarbon group is an alkoxy groupwith carbon number from 1 to 12 both inclusive,

the divalent hydrocarbon group is one of an alkylene group with carbonnumber from 1 to 12 both inclusive, an alkenylene group with carbonnumber from 2 to 12 both inclusive, an alkynylene group with carbonnumber from 2 to 12 both inclusive, an arylene group with carbon numberfrom 6 to 18 both inclusive, and a cycloalkylene group with carbonnumber from 3 to 18 both inclusive, and

the divalent oxygen-containing hydrocarbon group is a group thatincludes one or more ether bonds (—O—) and includes one or more of analkylene group with carbon number from 1 to 12 both inclusive, analkenylene group with carbon number from 2 to 12 both inclusive, analkynylene with carbon number from 2 to 12 both inclusive, an arylenegroup with carbon number from 6 to 18 both inclusive, and acycloclkylene group with carbon number from 3 to 18 both inclusive.

(6) The secondary battery according to any one of (1) to (5), wherein

the compound represented by the Formula (19) is one or more of compoundsrepresented by following Formula (19-1) to Formula (19-31), and

the compound represented by the Formula (20) is one or more of compoundsrepresented by following Formula (20-1) to Formula (20-28).

(7) The secondary battery according to any one of (1) to (6), wherein

the compound represented by the Formula (3) is one or more of compoundsrepresented by following Formula (3-1) to Formula (3-12),

the compound represented by the Formula (4) is one or more of compoundsrepresented by following Formula (4-1) to Formula (4-17), and

the compound represented by the Formula (5) is one or more of compoundsrepresented by following Formula (5-1) to Formula (5-9).

(8) The secondary battery according to any one of (1) to (7), wherein acontent of the cyano compound in the electrolytic solution is from about0.01 weight percent to about 20 weight percent both inclusive.(9) The secondary battery according to any one of (1) to (8), wherein acontent of the non-cyano compound in the electrolytic solution is fromabout 0.001 weight percent to about 2 weight percent both inclusive.(10) The secondary battery according to any one of (1) to (9), whereinthe secondary battery is a lithium secondary battery.(11) An electrolytic solution including

a cyano compound including a compound represented by a following Formula(19), a compound represented by a following Formula (20), or both, and

a non-cyano compound including one of a compound represented by afollowing Formula (3), a compound represented by a following Formula(4), a compound represented by a following Formula (5), a compoundrepresented by a following Formula (6), and a compound represented by afollowing Formula (7)

where R5 and R6 are each one of a hydrocarbon group, anoxygen-containing hydrocarbon group, a cyano-group-containing group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another, and the R5,the R6, or both include the cyano-group-containing group; a cyano groupin the cyano-group-containing group in the R5, the R6, or both is bondedto an oxygen atom (O) at a terminal of a —O—C(═O)—O— bond with one ormore carbon atoms (C) in between,

where R7 is one of a hydrocarbon group, an oxygen-containing hydrocarbongroup, a cyano-group-containing group, halogenated groups of theforegoing groups, and groups each obtained by bonding two or more of theforegoing groups to one another; R8 is one of a cyano-group-containinggroup, halogenated groups thereof, and groups each obtained by bondingtwo or more of the foregoing groups to one another; a cyano group in thecyano-group-containing group in R8 is bonded to an oxygen atom at aterminal of a —C(═O)—O— bond with one or more carbon atoms in between,

where R11 and R13 are each one of a monovalent hydrocarbon group, amonovalent oxygen-containing hydrocarbon group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another; and R12 is one of a divalenthydrocarbon group and halogenated groups thereof,

where R14 and R16 are each one of a monovalent hydrocarbon group, amonovalent oxygen-containing hydrocarbon group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another; R15 is one of a divalenthydrocarbon group and halogenated groups thereof; and n is an integerthat is 1 or larger,

where R17 and R19 are each one of a monovalent hydrocarbon group, amonovalent oxygen-containing hydrocarbon group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another; and R18 is one of a divalenthydrocarbon group and halogenated groups thereof.

LiPF₂O₂  (6)

Li₂PFO₃  (7)

(12) A battery pack including:

the secondary battery according to any one of (1) to (10);

a control section controlling a used state of the secondary battery; and

a switch section switching the used state of the secondary batteryaccording to an instruction of the control section.

(13) An electric vehicle including:

the secondary battery according to any one of (1) to (10);

a conversion section converting electric power supplied from thesecondary battery into drive power;

a drive section operating according to the drive power; and

a control section controlling a used state of the secondary battery.

(14) An electric power storage system including:

the secondary battery according to any one of (1) to (10);

one or more electric devices supplied with electric power from thesecondary battery; and

a control section controlling the supplying of the electric power fromthe secondary battery to the one or more electric devices.

(15) An electric power tool including:

the secondary battery according to any one of (1) to (10); and

a movable section supplied with electric power from the secondarybattery.

(16) An electronic apparatus including the secondary battery accordingto any one of (1) to (10) as an electric power supply source.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

The invention is claimed as follows:
 1. A secondary battery comprising:a cathode; an anode; and an electrolytic solution including a cyanocompound, the cyano compound including a compound represented by afollowing Formula (1), a compound represented by a following Formula(2), or both,

where R1 and R2 are each one of a saturated hydrocarbon group, anunsaturated hydrocarbon group, an oxygen-containing saturatedhydrocarbon group, a cyano-group-containing group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another, and the R1, the R2, or both includethe cyano-group-containing group; a cyano group in thecyano-group-containing group is bonded to an oxygen atom (O) at aterminal of a —O—C(═O)—O— bond with one or more carbon atoms (C) inbetween; (A) when one of the R1 and the R2 does not include thecyano-group-containing group but includes an unsaturated carbon bond andthe other of the R1 and the R2 includes the cyano-group-containinggroup, number of the cyano group in the other of the R1 and the R2 isone or larger; (B) when one of the R1 and the R2 include neither thecyano-group-containing group nor the unsaturated carbon bond and theother of the R1 and the R2 includes the cyano-group-containing group andthe unsaturated carbon bond, the number of the cyano group in the otherof the R1 and the R2 is one or larger; and (C) when one of the R1 andthe R2 include neither the cyano-group-containing group nor theunsaturated carbon bond and the other of the R1 and the R2 includes thecyano-group-containing group but does not include the unsaturated carbonbond, the number of the cyano group in the other of the R1 and the R2 istwo or larger,

where R3 is one of a saturated hydrocarbon group, an unsaturatedhydrocarbon group, an oxygen-containing saturated hydrocarbon group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another; R4 is one ofa cyano-group-containing group, halogenated groups thereof, and groupseach obtained by bonding two or more of the foregoing groups to oneanother; a cyano group in the cyano-group-containing group is bonded toan oxygen atom at a terminal of a —C(═O)—O-bond with one or more carbonatoms in between; (D) when the R3 includes an unsaturated carbon bond,number of the cyano group in the R4 is one or larger; (E) when the R3does not include the unsaturated carbon bond and the R4 includes theunsaturated carbon bond, the number of the cyano group in the R4 is oneor larger; and (F) when the R3 does not include the unsaturated carbonbond and the R4 does not include the unsaturated carbon bond, the numberof the cyano group in the R4 is two or larger.
 2. The secondary batteryaccording to claim 1, wherein the cyano-group-containing group is one ofa group obtained by substituting each of part or all of hydrogen groupsin a saturated hydrocarbon group by a cyano group and a group obtainedby substituting each of part or all of hydrogen groups in an unsaturatedhydrocarbon group by a cyano group.
 3. The secondary battery accordingto claim 2, wherein the saturated hydrocarbon group is an alkyl groupwith carbon number from 1 to 12 both inclusive, and the unsaturatedhydrocarbon group is an aryl group with carbon number from 6 to 18 bothinclusive.
 4. The secondary battery according to claim 1, wherein thesaturated hydrocarbon group is one of an alkyl group with carbon numberfrom 1 to 12 both inclusive and a cycloalkyl group with carbon numberfrom 3 to 18 both inclusive, the unsaturated hydrocarbon group is one ofan alkenyl group with carbon number from 2 to 12 both inclusive, analkynyl group with carbon number from 2 to 12 both inclusive, and anaryl group with carbon number from 6 to 18 both inclusive, theoxygen-containing saturated hydrocarbon group is an alkoxy group withcarbon number from 1 to 12 both inclusive, and the halogenated groupseach include, as a halogen group, one or more of a fluorine group, achlorine group, a bromine group, and an iodine group.
 5. The secondarybattery according to claim 1, wherein the compound represented by theFormula (1) is one or more of compounds represented by following Formula(1-1) to Formula (1-25), and the compound represented by the Formula (2)is one or more of compounds represented by following Formula (2-1) toFormula (2-21).


6. The secondary battery according to claim 1, wherein a content of thecyano compound in the electrolytic solution is from about 0.01 weightpercent to about 20 weight percent both inclusive.
 7. The secondarybattery according to claim 1, wherein the electrolytic solution includesa non-cyano compound, and the non-cyano compound includes one or more ofa compound represented by a following Formula (3), a compoundrepresented by a following Formula (4), a compound represented by afollowing Formula (5), a compound represented by a following Formula(6), and a compound represented by a following Formula (7),

where R11 and R13 are each one of a monovalent hydrocarbon group, amonovalent oxygen-containing hydrocarbon group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another; and R12 is one of a divalenthydrocarbon group and halogenated groups thereof,

where R14 and R16 are each one of a monovalent hydrocarbon group, amonovalent oxygen-containing hydrocarbon group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another; R15 is one of a divalenthydrocarbon group and halogenated groups thereof; and n is an integerthat is 1 or larger,

where R17 and R19 are each one of a monovalent hydrocarbon group, amonovalent oxygen-containing hydrocarbon group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another; and R18 is one of a divalenthydrocarbon group and halogenated groups thereof.LiPF₂O₂  (6)Li₂PFO₃  (7)
 8. The secondary battery according to claim 7, wherein themonovalent hydrocarbon group and the monovalent oxygen-containinghydrocarbon group encompass an alkyl group with carbon number from 1 to12 both inclusive, an alkenyl group with carbon number from 2 to 12 bothinclusive, an alkynyl group with carbon number from 2 to 12 bothinclusive, an aryl group with carbon number from 6 to 18 both inclusive,a cycloalkyl group with carbon number from 3 to 18 both inclusive, andan alkoxy group with carbon number from 1 to 12 both inclusive, thedivalent hydrocarbon group is one of an alkylene group with carbonnumber from 1 to 12 both inclusive, an alkenylene group with carbonnumber from 2 to 12 both inclusive, an alkynylene group with carbonnumber from 2 to 12 both inclusive, an arylene group with carbon numberfrom 6 to 18 both inclusive, a cycloalkylene group with carbon numberfrom 3 to 18 both inclusive, groups each obtained by bonding two or moreof the foregoing groups to one another, and groups each including one ormore of the foregoing groups and an ether bond (—O—), and thehalogenated group includes, as a halogen group, one or more of afluorine group, a chlorine group, a bromine group, and an iodine group.9. The secondary battery according to claim 7, wherein the compoundrepresented by the Formula (3) is one or more of compounds representedby following Formula (3-1) to Formula (3-12), the compound representedby the Formula (4) is one or more of compounds represented by followingFormula (4-1) to Formula (4-17), and the compound represented by theFormula (5) is one or more of compounds represented by following Formula(5-1) to Formula (5-9).


10. The secondary battery according to claim 7, wherein a content of thenon-cyano compound in the electrolytic solution is from about 0.001weight percent to about 2 weight percent both inclusive.
 11. Thesecondary battery according to claim 1, wherein the secondary battery isa lithium secondary battery.
 12. An electrolytic solution comprising acyano compound including a compound represented by a following Formula(1), a compound represented by a following Formula (2), or both,

where R1 and R2 are each one of a saturated hydrocarbon group, anunsaturated hydrocarbon group, an oxygen-containing saturatedhydrocarbon group, a cyano-group-containing group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another, and the R1, the R2, or both includethe cyano-group-containing group; a cyano group in thecyano-group-containing group is bonded to an oxygen atom (O) at aterminal of a —O—C(═O)—O— bond with one or more carbon atoms (C) inbetween; (A) when one of the R1 and the R2 does not include thecyano-group-containing group but includes an unsaturated carbon bond andthe other of the R1 and the R2 includes the cyano-group-containinggroup, number of the cyano group in the other of the R1 and the R2 isone or larger; (B) when one of the R1 and the R2 include neither thecyano-group-containing group nor the unsaturated carbon bond and theother of the R1 and the R2 includes the cyano-group-containing group andthe unsaturated carbon bond, the number of the cyano group in the otherof the R1 and the R2 is one or larger; and (C) when one of the R1 andthe R2 include neither the cyano-group-containing group nor theunsaturated carbon bond and the other of the R1 and the R2 includes thecyano-group-containing group but does not include the unsaturated carbonbond, the number of the cyano group in the other of the R1 and the R2 istwo or larger,

where R3 is one of a saturated hydrocarbon group, an unsaturatedhydrocarbon group, an oxygen-containing saturated hydrocarbon group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another; R4 is one ofa cyano-group-containing group, halogenated groups thereof, and groupseach obtained by bonding two or more of the foregoing groups to oneanother; a cyano group in the cyano-group-containing group is bonded toan oxygen atom at a terminal of a —C(═O)—O-bond with one or more carbonatoms in between; (D) when the R3 includes an unsaturated carbon bond,number of the cyano group in the R4 is one or larger; (E) when the R3does not include the unsaturated carbon bond and the R4 includes theunsaturated carbon bond, the number of the cyano group in the R4 is oneor larger; and (F) when the R3 does not include the unsaturated carbonbond and the R4 does not include the unsaturated carbon bond, the numberof the cyano group in the R4 is two or larger.
 13. A battery packcomprising: a secondary battery; a control section controlling a usedstate of the secondary battery; and a switch section switching the usedstate of the secondary battery according to an instruction of thecontrol section, wherein the secondary battery includes a cathode, ananode, and an electrolytic solution including a cyano compound, thecyano compound including a compound represented by a following Formula(1), a compound represented by a following Formula (2), or both,

where R1 and R2 are each one of a saturated hydrocarbon group, anunsaturated hydrocarbon group, an oxygen-containing saturatedhydrocarbon group, a cyano-group-containing group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another, and the R1, the R2, or both includethe cyano-group-containing group; a cyano group in thecyano-group-containing group is bonded to an oxygen atom (O) at aterminal of a —O—C(═O)—O— bond with one or more carbon atoms (C) inbetween; (A) when one of the R1 and the R2 does not include thecyano-group-containing group but includes an unsaturated carbon bond andthe other of the R1 and the R2 includes the cyano-group-containinggroup, number of the cyano group in the other of the R1 and the R2 isone or larger; (B) when one of the R1 and the R2 include neither thecyano-group-containing group nor the unsaturated carbon bond and theother of the R1 and the R2 includes the cyano-group-containing group andthe unsaturated carbon bond, the number of the cyano group in the otherof the R1 and the R2 is one or larger; and (C) when one of the R1 andthe R2 include neither the cyano-group-containing group nor theunsaturated carbon bond and the other of the R1 and the R2 includes thecyano-group-containing group but does not include the unsaturated carbonbond, the number of the cyano group in the other of the R1 and the R2 istwo or larger,

where R3 is one of a saturated hydrocarbon group, an unsaturatedhydrocarbon group, an oxygen-containing saturated hydrocarbon group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another; R4 is one ofa cyano-group-containing group, halogenated groups thereof, and groupseach obtained by bonding two or more of the foregoing groups to oneanother; a cyano group in the cyano-group-containing group is bonded toan oxygen atom at a terminal of a —C(═O)—O-bond with one or more carbonatoms in between; (D) when the R3 includes an unsaturated carbon bond,number of the cyano group in the R4 is one or larger; (E) when the R3does not include the unsaturated carbon bond and the R4 includes theunsaturated carbon bond, the number of the cyano group in the R4 is oneor larger; and (F) when the R3 does not include the unsaturated carbonbond and the R4 does not include the unsaturated carbon bond, the numberof the cyano group in the R4 is two or larger.
 14. An electric vehiclecomprising: a secondary battery; a conversion section convertingelectric power supplied from the secondary battery into drive power; adrive section operating according to the drive power; and a controlsection controlling a used state of the secondary battery, wherein thesecondary battery includes a cathode, an anode, and an electrolyticsolution including a cyano compound, the cyano compound including acompound represented by a following Formula (1), a compound representedby a following Formula (2), or both,

where R1 and R2 are each one of a saturated hydrocarbon group, anunsaturated hydrocarbon group, an oxygen-containing saturatedhydrocarbon group, a cyano-group-containing group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another, and the R1, the R2, or both includethe cyano-group-containing group; a cyano group in thecyano-group-containing group is bonded to an oxygen atom (O) at aterminal of a —O—C(═O)—O— bond with one or more carbon atoms (C) inbetween; (A) when one of the R1 and the R2 does not include thecyano-group-containing group but includes an unsaturated carbon bond andthe other of the R1 and the R2 includes the cyano-group-containinggroup, number of the cyano group in the other of the R1 and the R2 isone or larger; (B) when one of the R1 and the R2 include neither thecyano-group-containing group nor the unsaturated carbon bond and theother of the R1 and the R2 includes the cyano-group-containing group andthe unsaturated carbon bond, the number of the cyano group in the otherof the R1 and the R2 is one or larger; and (C) when one of the R1 andthe R2 include neither the cyano-group-containing group nor theunsaturated carbon bond and the other of the R1 and the R2 includes thecyano-group-containing group but does not include the unsaturated carbonbond, the number of the cyano group in the other of the R1 and the R2 istwo or larger,

where R3 is one of a saturated hydrocarbon group, an unsaturatedhydrocarbon group, an oxygen-containing saturated hydrocarbon group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another; R4 is one ofa cyano-group-containing group, halogenated groups thereof, and groupseach obtained by bonding two or more of the foregoing groups to oneanother; a cyano group in the cyano-group-containing group is bonded toan oxygen atom at a terminal of a —C(═O)—O-bond with one or more carbonatoms in between; (D) when the R3 includes an unsaturated carbon bond,number of the cyano group in the R4 is one or larger; (E) when the R3does not include the unsaturated carbon bond and the R4 includes theunsaturated carbon bond, the number of the cyano group in the R4 is oneor larger; and (F) when the R3 does not include the unsaturated carbonbond and the R4 does not include the unsaturated carbon bond, the numberof the cyano group in the R4 is two or larger.
 15. An electric powerstorage system comprising: a secondary battery; one or more electricdevices supplied with electric power from the secondary battery; and acontrol section controlling the supplying of the electric power from thesecondary battery to the one or more electric devices, wherein thesecondary battery includes a cathode, an anode, and an electrolyticsolution including a cyano compound, the cyano compound including acompound represented by a following Formula (1), a compound representedby a following Formula (2), or both,

where R1 and R2 are each one of a saturated hydrocarbon group, anunsaturated hydrocarbon group, an oxygen-containing saturatedhydrocarbon group, a cyano-group-containing group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another, and the R1, the R2, or both includethe cyano-group-containing group; a cyano group in thecyano-group-containing group is bonded to an oxygen atom (O) at aterminal of a —O—C(═O)—O— bond with one or more carbon atoms (C) inbetween; (A) when one of the R1 and the R2 does not include thecyano-group-containing group but includes an unsaturated carbon bond andthe other of the R1 and the R2 includes the cyano-group-containinggroup, number of the cyano group in the other of the R1 and the R2 isone or larger; (B) when one of the R1 and the R2 include neither thecyano-group-containing group nor the unsaturated carbon bond and theother of the R1 and the R2 includes the cyano-group-containing group andthe unsaturated carbon bond, the number of the cyano group in the otherof the R1 and the R2 is one or larger; and (C) when one of the R1 andthe R2 include neither the cyano-group-containing group nor theunsaturated carbon bond and the other of the R1 and the R2 includes thecyano-group-containing group but does not include the unsaturated carbonbond, the number of the cyano group in the other of the R1 and the R2 istwo or larger,

where R3 is one of a saturated hydrocarbon group, an unsaturatedhydrocarbon group, an oxygen-containing saturated hydrocarbon group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another; R4 is one ofa cyano-group-containing group, halogenated groups thereof, and groupseach obtained by bonding two or more of the foregoing groups to oneanother; a cyano group in the cyano-group-containing group is bonded toan oxygen atom at a terminal of a —C(═O)-β-bond with one or more carbonatoms in between; (D) when the R3 includes an unsaturated carbon bond,number of the cyano group in the R4 is one or larger; (E) when the R3does not include the unsaturated carbon bond and the R4 includes theunsaturated carbon bond, the number of the cyano group in the R4 is oneor larger; and (F) when the R3 does not include the unsaturated carbonbond and the R4 does not include the unsaturated carbon bond, the numberof the cyano group in the R4 is two or larger.
 16. An electric powertool comprising: a secondary battery; and a movable section suppliedwith electric power from the secondary battery, wherein the secondarybattery includes a cathode, an anode, and an electrolytic solutionincluding a cyano compound, the cyano compound including a compoundrepresented by a following Formula (1), a compound represented by afollowing Formula (2), or both,

where R1 and R2 are each one of a saturated hydrocarbon group, anunsaturated hydrocarbon group, an oxygen-containing saturatedhydrocarbon group, a cyano-group-containing group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another, and the R1, the R2, or both includethe cyano-group-containing group; a cyano group in thecyano-group-containing group is bonded to an oxygen atom (O) at aterminal of a —O—C(═O)—O— bond with one or more carbon atoms (C) inbetween; (A) when one of the R1 and the R2 does not include thecyano-group-containing group but includes an unsaturated carbon bond andthe other of the R1 and the R2 includes the cyano-group-containinggroup, number of the cyano group in the other of the R1 and the R2 isone or larger; (B) when one of the R1 and the R2 include neither thecyano-group-containing group nor the unsaturated carbon bond and theother of the R1 and the R2 includes the cyano-group-containing group andthe unsaturated carbon bond, the number of the cyano group in the otherof the R1 and the R2 is one or larger; and (C) when one of the R1 andthe R2 include neither the cyano-group-containing group nor theunsaturated carbon bond and the other of the R1 and the R2 includes thecyano-group-containing group but does not include the unsaturated carbonbond, the number of the cyano group in the other of the R1 and the R2 istwo or larger,

where R3 is one of a saturated hydrocarbon group, an unsaturatedhydrocarbon group, an oxygen-containing saturated hydrocarbon group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another; R4 is one ofa cyano-group-containing group, halogenated groups thereof, and groupseach obtained by bonding two or more of the foregoing groups to oneanother; a cyano group in the cyano-group-containing group is bonded toan oxygen atom at a terminal of a —C(═O)—O-bond with one or more carbonatoms in between; (D) when the R3 includes an unsaturated carbon bond,number of the cyano group in the R4 is one or larger; (E) when the R3does not include the unsaturated carbon bond and the R4 includes theunsaturated carbon bond, the number of the cyano group in the R4 is oneor larger; and (F) when the R3 does not include the unsaturated carbonbond and the R4 does not include the unsaturated carbon bond, the numberof the cyano group in the R4 is two or larger.
 17. An electronicapparatus comprising a secondary battery as an electric power supplysource, wherein the secondary battery includes a cathode, an anode, andan electrolytic solution including a cyano compound, the cyano compoundincluding a compound represented by a following Formula (1), a compoundrepresented by a following Formula (2), or both,

where R1 and R2 are each one of a saturated hydrocarbon group, anunsaturated hydrocarbon group, an oxygen-containing saturatedhydrocarbon group, a cyano-group-containing group, halogenated groups ofthe foregoing groups, and groups each obtained by bonding two or more ofthe foregoing groups to one another, and the R1, the R2, or both includethe cyano-group-containing group; a cyano group in thecyano-group-containing group is bonded to an oxygen atom (O) at aterminal of a —O—C(═O)—O— bond with one or more carbon atoms (C) inbetween; (A) when one of the R1 and the R2 does not include thecyano-group-containing group but includes an unsaturated carbon bond andthe other of the R1 and the R2 includes the cyano-group-containinggroup, number of the cyano group in the other of the R1 and the R2 isone or larger; (B) when one of the R1 and the R2 include neither thecyano-group-containing group nor the unsaturated carbon bond and theother of the R1 and the R2 includes the cyano-group-containing group andthe unsaturated carbon bond, the number of the cyano group in the otherof the R1 and the R2 is one or larger; and (C) when one of the R1 andthe R2 include neither the cyano-group-containing group nor theunsaturated carbon bond and the other of the R1 and the R2 includes thecyano-group-containing group but does not include the unsaturated carbonbond, the number of the cyano group in the other of the R1 and the R2 istwo or larger,

where R3 is one of a saturated hydrocarbon group, an unsaturatedhydrocarbon group, an oxygen-containing saturated hydrocarbon group,halogenated groups of the foregoing groups, and groups each obtained bybonding two or more of the foregoing groups to one another; R4 is one ofa cyano-group-containing group, halogenated groups thereof, and groupseach obtained by bonding two or more of the foregoing groups to oneanother; a cyano group in the cyano-group-containing group is bonded toan oxygen atom at a terminal of a —C(═O)—O— bond with one or more carbonatoms in between; (D) when the R3 includes an unsaturated carbon bond,number of the cyano group in the R4 is one or larger; (E) when the R3does not include the unsaturated carbon bond and the R4 includes theunsaturated carbon bond, the number of the cyano group in the R4 is oneor larger; and (F) when the R3 does not include the unsaturated carbonbond and the R4 does not include the unsaturated carbon bond, the numberof the cyano group in the R4 is two or larger.